在產業中有多家廠商生產力異質的情況下，本文分析在政府不同特性的補貼政策（定額與從量補貼）中，選擇性與全面性補貼對社會福利的影響。本文證明當補貼程度高於特定水準時，選擇性補貼的福利水準將高於全面性補貼，而且高成本廠商的生產力越差，產業中獲得補貼的總家數就應該越少。不過高成本廠商家數佔產業總家數比例越高時，則應獲得補貼的家數就應該要越多。我們也證明補貼程度越高，受補貼總家數就要越少。當補貼程度低於特定水準時，則所有高成本廠商皆應獲得補貼，而且此時福利水準的高低將與補貼程度呈現正向關係。最後，唯有補貼程度等於某特定水準時，全面性補貼下的福利才會與選擇性補貼下的福利水準相等。本文也對從量與定額補貼政策的福利效果作政策排序分析。

We analyze the welfare effect of a selective and a comprehensive subsidy policy. We find that the selective subsidy policy has a higher welfare than the comprehensive subsidy policy does when the subsidy level is high enough. In addition, the number of subsidized firms should be fewer if the productivity of high-cost firms is low. Also, the number of subsidized firms increases with the proportion of high-cost firms in the industry. We further prove that the government should limit subsidized firms when the subsidy level becomes higher. When the subsidy level is low enough, the government should subsidize all high-cost firms and the welfare level is positively related with the subsidy level. Besides, only if the subsidy level reaches a critical value, the social welfare by the comprehensive subsidy policy is equivalent to that by the selective subsidy policy.