中文摘要：

本文从理论上分析了股权结构与公司价值间的关系，并通过实证研究考察上市公司所有权结构及由此而产生的代理成本与其市场价值之间的关系。检验结果与理论分析相一致：（1）上市公司存在控股股东，会使公司市场价值折价。（2）上市公司存在股权制衡，能够有效的减少公司代理成本，提升公司价值。（3）不同性质的控股股东所产生的代理成本不同，国家股东的非人格化使得公司的代理成本高于非国有股东。本文得出结论：我国的上市公司普遍存在控股股东，由此产生的代理成本减低了企业的价值，国有股东的代理问题尤为严重，股权制衡的模式能够在一定程度上缓解代理问题。

英文摘要：

We analyze the ownership structure and the relationship between the value of the company, study ownership structure of listed companies and the resulting agency costs between the market value of their relationship by empirical research. Our empirical results are consistent with theoretical analysis ： （ 1 ） there are discounts on Tobin＇ s q among the firms with controlling shareholders. （ 2 ） Firms with multiple block shareholders have higher market valuation. （ 3 ） the agency costs generated by controlling shareholders vary across controller identities. So we conclude that ： China＇ s listed companies of controlling shareholders in the prevalence, agency costs reduce the value of the enterprise, state - owned shareholder proxy is a particularly serious problem which stock share balance mode may alleviate the agency problem.