The environment of medical industry in Taiwan is unprecedented rigorous. Except the finance pressure of medical expense billing and the increasing demand of the quality of medical service, recently due to the change of government health insurance policy, each medical organization strives for the rare resource and limited customer, not only start changing the type of the medical service, but also emphasis on improving the function of hospital management and controlling the cost. Formerly, purchasing simply means buying goods; but now, for the rigorous medical management environment and the rapid pace of innovation, purchasing clerk is required constant skill upgrading, such as leasing, loaning, BOT and outsourcing by contract, to obtain the use of goods and to satisfy the aim of demand. Additionally, the way to obtain the operation or ownership of goods is different from the former way. Contributed to the change, it presents its importance in business management. So, this research wants to investigate the relationship of human capital, knowledge sharing will, purchasing ability and purchasing performance. We applied exploratory and confirmatory analysis to investigate the relationship involved. The samples were purchasing clerks of hospital, including medical centers, regional hospitals and area hospitals. Out of 400 questionnaires were sent, the valid questionnaires returned were 114. Factor analysis , variable analysis, regression analysis were used to process the data acquired. The major findings of the research are summarized as follows: (1) the human capital of purchasing clerk is positive effect to purchasing ability and purchasing performance. (2) knowledge sharing will is positive effect to purchasing ability and purchasing performance (3)purchasing ability is positive effect to purchasing performance (4) purchasing ability has the mediate effect among human capital and knowledge sharing will with purchasing performance.