Compared with explicit knowledge,tacit knowledge is much more perfect and can be used to create valuable things.The ability of exploiting and utilizing tacit knowledge has become the significant factor to success for an individual or an organization.Private scientific and technological enterprises,as one of the main parts of national economy in China,desire to transfer the internal tacit knowledge into the productivity in the reality.The paper analyzes the nature of tacit knowledge and the factors that restrict the share of tacit knowledge in private scientific and technological enterprises in detail from individual,group and organization based on infrastructure of tacit knowledge.