The small and mediumsized enterprises often lack those characteristics of integration，forecasting，systematization，pertinence and operability，guidance and flexibility，hierarchy and sequentiality during the process of designing the internal control system. Based on these，the internal control system is in low level which can not be able to make contribution to a healthy enterprise developing. Therefore，the small and medium-sized enterprises should closely combine the enterprises itself and outside situation as well as define principles，strengthen contents，weight programmes in the process of designing the internal control systems.