中文摘要：

国有企业分类改革与混合所有制改革是国有企业改革的两大热点,需要有机结合起来。基于双寡头垄断竞争模型,按照国有企业类别研究不同市场环境下的国有股最优比例。结果表明,国有股最优比例是一个动态变量,受政府目标、竞争类型、国有资本及引进的非国有资本效率等多种因素影响,尤其是引入的非国有资本效率及市场竞争环境是制约国有股最优比例的两个最重要因素。因而应加快推进国有企业分类改革,因地制宜推进国有企业混合所有制改革,引进优质非国有资本,优化国有企业股权结构。

英文摘要：

The classification reforin and the mixed ownership reform of the state-owned enterprises are the two hot spots of the state-owned enterprises reform, which need to be combined. Based on the duopoly model and according to the category of state-owned enterprises, the paper studies the optimal proportion of state- owned shares in different market environments. The research results show that the optimal proportion of state- owned shares is a dynamic variable and is influenced by various factors including the government targets and the competition types and the efficiencies of the non-state capital and state capital, and the introduced non- state capital efficiency and market competitive environments are the most important factors of restricting the optimal proportion of state-owned shares. So it is necessary to accelerate the reform of state-owned enterprise classification, adjust measures to local conditions to advance the mixed ownership reform of state-owned enterprises, and introduce high-quality non-state-owned capital to optimize the structure of state-owned enterprises.