中文摘要：

在传统委托-代理理论基础上,根据主次委托人在委托-代理关系中的不同作用,建立存在主次委托人条件下的委托-代理模型,并利用实验数据对模型结果进行实验检验。研究结果表明,当代理人为次委托人付出的努力水平对主委托人存在外部性时,主委托人支付给代理人的最优激励性报酬和代理人为主委托人付出的最优努力水平都将高于单一委托人条件下的情况;当代理人为次委托人付出的努力水平对主委托人存在正（负）外部性时,主委托人获得的预期收益将大于（小于）其在单一委托人条件下获得的预期收益;代理人在存在主次委托人条件下获得的预期总收益将高于其在单一委托人条件下获得的预期总收益。论文基于主次委托人在委托-代理关系中的不同地位拓展和深化了传统委托-代理理论。

英文摘要：

In the real world, an agent usually has a primary principal and a secondary principal at the same time, and there exist different principal-agent relationships between the primary principal, the secondary principal and the agent respectively. Drawing on the agent＇s utility function and effort cost function pro- vided by Siqueira, Sandler and Cauley（2009）, a principal-agent model is set under the condition of existing primary and secondary principals on the basis of traditional principal-agent theories and different roles of primary and secondary principals in the principal-agent relationship, and gets the optimal incentive com- pensation paid to the agent by the primary principal and the agent＇s optimal effort level for the primary principal is otiained, and the comparative analysis is carried on the principal-agent relationships under the condition of existing primary and secondary principals and that under the condition of a single principal based on the above-mentioned model. Then, taking MBA students, EMBA students, senior managers training students, MPAcc students, doctoral candidates, master degree candidates and undergraduates of our university as experimental subjects, experimental data is collected by interviews and questionnaire to make the experimental test of the model results. The main theoretical and experimental research results are as follows. Firstly, when the agent＇s effort for the secondary principal has externalities to the primary principal, the incentive compensation paid to the agent by the primary principal and the agent＇s optimal ef- fort level for the primary principal will be higher than that under a single principal respectively. Secondly, when the agent＇s effort for the secondary principal has positive （or negative） externalities to the primary principal, the primary principal will gain more （or less） expected earning than that under a single princi- pal. Thirdly, when the agent＇s effort for the secondary principal does not exist externalities to the primary pr