中文摘要：

结合中国股市2003—2014年面板数据,本文从企业微观决策角度考察企业资本结构最优决策,得到以下结论：（1）理论方面,税盾效应越大、破产清算价格越大,资本结构就越大,而债务成本越大、清算时的资本折旧率越大以及破产概率越大,企业资本结构就会越小;同时随着资产规模的增加企业资本结构会相应增加,当超过某一阀值后资本结构反而会减小。（2）实证方面,本文验证资产规模与资本结构之间的非线性关系,发现资本结构受到税盾效应和信贷供给的显著影响,而债务成本对资本结构的影响不显著。同时,中国股市资本结构的行业特征得到验证。

英文摘要：

Based on the panel data of China＇s stock market from 2003 to 2014,this paper investigates the optimal decision of enterprises＇ capital structure from the perspective of micro - decision - making. The results are as follows. （1） Theoretically, the greater the effect of tax shield, the higher the bankruptcy liquidation price, the bigger the capital structure; and the greater the cost of debt, the higher the depreciation rate at the time of liquidation and the greater the probability of bankruptcy, the smaller the enterprises＇ capital structure rate. Meanwhile, with the increase in the size of assets, enterprises＇ capital structure rate will increase accordingly, and when exceeding a certain threshold, the capital structure rate will be reduced instead. （2） Empirically, this paper verifies the non -linear relationship between the asset size and the capital structure rate ,finding that the capital structure rate is significantly affected by tax shield effects and credit supply, and debt cost has no significant effect on capital structure rate. Meanwhile, the industry characteristics of the capital structure rate of China＇s stock market are also verified.