本文采用委托人福利损失作为衡量委托代理问题中代理成本的指标,就双重委托代理问题中的股权结构与代理成本之间的关系进行了理论分析。本文采用1999～2009年的中国上市公司的相关数据对理论假设进行了实际验证,结果显示了对我国上市公司而言,股权集中度和控股股东持股比例的降低可以有效地降低代理成本,从而提升公司业绩。 In this paper, the welfare loss of the principal is used as the index to measure the agency cost in the principal-agent problem, and the relationship between the ownership structure and the agency cost in the dual-agent problem is analyzed theoretically. This paper uses the relevant data of Chinese listed companies from 1999 to 2009 to verify the theoretical assumptions. The results show that for listed companies in China, the reduction of ownership concentration and the controlling shareholder’s shareholding ratio can effectively reduce agency costs. Improve company performance.