This paper presents a method for a lean platform modeling technology for sales activities collaborative management according to the requirement of small-to-medium size (STMS) companies in China on distributed sales activities collaborative management and sales data consolidated management. In the application, STMS companies normally sell their products via some direct sales channels built by them, e.g., sales offices, or sub-companies which spread around different cities. In the paper, the method of the expected lean collaborative management system modeling is discussed; the principle of collaborative data synchronizing is illustrated, and the data structure design used for the management activities and related information storing is given including the strategy for event synchronizing. In a real example, the application of the proposed method is explained and it is proved that it has some remarkable advantages of low system implementation cost, customized functionalities, and short software development time after the given example system has passed integration tested.