The importance of employees' knowledge training was expatiated, and the deficiencies of employees' knowledge training management were pointed out firstly. On the base of this, it was figured out that, if enterprise carries out knowledge training effectively, it must understand the knowledge lack of employees firstly, and then analyze the employees' knowledge requirements scientifically. In this paper, the relevant concepts of knowledge reduction were introduced, and the decision-making algorithm of employees' knowledge training requirement was proposed on the basis of knowledge reduction and applied into salesmen's knowledge training requirement analysis in enterprise.