The definition of accounting: Management accounting is that companies to strengthen internal management and the realize of the aim of maximum profit in western , using various methods, collecting, processing and manage authorities’plan reasonably and information needed to control the economic process effectively , around three centers: cost, profit and capital, analysis the thing in the past, a branch of accounting that plan for the future.The brief history of development of Management accounting: (1) The era of the efficiency of the management accounting (the beginning of the 20th century to the '50 s) (2)The era of benefit of management accounting (the 80 s and 1950 s), (3)The era of management accounting’s reflection (1980 s), (4)The era of management accounting”s transition (1990 s)The functions of managers: (1) Planning, planning is that managers identify and select appropriate goals and put into effect. (2) The functions of organization, the organization is a process that managers to build a framework of a working relationship so as to enablemembers to work together and achieve the goal. (3) The functions of leadership ,leadership is to describe a future that managers to staff a clear vision, mobilize the initiative of the members in the organization, make them understand themselves in the organization. (4)The functions of controlling, the controlling is that manager evaluate the organization situation and determine what kind of action to maintain and improve performance.Examples : In terms of sales and revenue, as the national macroeconomic regulation and control, the ability of enterprises’financing is also more difficult, it can only use the limited funds, which makes the enterprise’s debt problem increasingly serious. In terms of cost, due to opening up the market stage, the promotional cost is high. In the face of all these situations, company K must take relative strain measures to improve their competitive advantages, management accounting attaches great importances to the external environment and market, pay attention to characteristics such as integrity and the methods of flexibility, it is accord with the requirement of company K’s strain strategy. And, in all reflect of thecompany's operating data, accounting data accounts for 60 to 70%. So K company decided from accounting aspects, through the use of management accounting, to help analyze the environment of market and their own advantages, to develop a marketing strategy with the actual situation of enterprise, and adopt a series of effective measures to implement the strategic goals.Importance of good decision:First, decision is the foundation of the management of enterprises .Decisions is the choice of selecting a solution, as a guide to the future behavior, as long as we can analyze of and plan the research. No decision and no rational action, decision-making is the core of planning. And one of the characteristics of the planning is the dominant planning job, it is the foundation of organized, such as, guidance and leadership, control work , therefore, in this sense, decision making is the basis of the management.Second, the decision is a priority for the competent, household workers.Decision making is not just a matter of supervisorypersonnel, on to the tallest leadership of the enterprise, next to the team leader, they should make decisions, just different from the importance of the decision and influence scope. In actual management works, the decision is the first task of executives, it has been widespread. Simon said: "the management is the decision".It means that decision-making is the priority for the management of all types and at all levels.The examples of poor decision: The financial regulator for Britain, published a report on Monday, pointing to poor decision by its management and board as cause of the failure of the Royal Bank of Scotland (RBS) in2008.FSA attributed the bank's failure to six factors including significant weaknesses in capital position, over-reliance on risky short-term wholesale funding, concerns andun certainties about the underlying asset quality and substantial losses in credit trading activities.The introduction of the Royal Bank of Scotland: The royal bank of Scotland group was built in 1727, its head office is in Edinburgh, UK, it is Europe's leading financial servicesgroup, also is the UK's largest bank, its business throughout Britain and the world. The bank in the UK ranked first in the banking sector in aspects of legal person, individual and overseas, ranked second in retail banking and private car insurance industry.Reference：[1]Discussing the role of strategic management accounting’s growth in our country [J]. Science & Technology Ecnony Market.2008；3[2]The role of strategic guiding to the research of basic management accounting [J]. Market Modernization，2006；12[3]the role of strategic management accounting to promote enterprise’s core competitiveness[J].The tax of Fujian ，2003；10[4]The core competencies of management accounting in the enterprise [J]. Northern Economy and Trade，2001；9 [5]People daily online, /90777/7674085.html [6]Wikipedia,/wiki/Management_acc ounting。