Begin with the analysis of motivation dilemma in the process of the transfer and share of tacit knowledge,then by combining motivation theory and knowledge management theory,a model based on two dimensions about the characteristics of tacit knowledge,one is tacitness and the other is systemization, is put forth.These two characteristics have effect on the choice of intrinsic motivation and extrinsic motivation,and on the choice of theoretic foundationfrom the point of agency cost or from the point of competitive advantage.Two constraints on the motivation mechanism design are also considered,that is,performance measurement difficulty and uncertainty.