在許多開發中國家,政府為保護國內產業會限制外國企業於本國投資時須有一定國內股份,如中國;本文在一國際混合寡占模型下討論最適民營化比例與股權管制的影響。我們發現嚴厲股權管制措施會增加民營企業產出、利潤、市場價格和社會福利,但會降低公營企業的產出;又隨著股權管制的增加,政府將提升民營化的程度;此外,廠商家數越高亦將提升政府民營化的程度。To protect domestic firms in a single market, the government could controldomestic equity for foreign competitors. In this paper, we consider in a mixed marketwith a homogeneous good, government decides two policies: the degree ofprivatization and control on domestic equity for foreign competitors. We have shownthat the stringent control on domestic equity of foreign firms increases private firms’outputs, profits, market price and social welfare, but decreases public firm’s output.Furthermore, along with the stringent control on the domestic equity of foreign firms,the government should increase the degree of privatization. In an opening market,intensive competition from private firms in general will enhance the degree ofprivatization.