Making use of econometric models in Shandong province of China, the paper verifies a method which can calculate the scale of positive externality measured in currency caused by enterprises’ activity, and evaluates the performance of government fiscal expenditure for energy conservation and environmental protection in internalizing the positive externality of enterprises’ activity in industrial system. Firstly, with the aid of the economic implications of econometric model parameters and the coefficient of determination, we separate the share of resource saving and the pollutant emission reduction caused by government fiscal expenditure from the total industrial resource saving and pollutant emission reduction; secondly, the environmental value of unit pollutant emission reduction and unit resource saving is estimated by using the data of the amount of pollutants removed from the regional industrial system and the operating costs of the relevant facilities; thirdly, with the aid of data on this expenditure and environmental value of unit pollutant emission reduction and unit resource saving, we monetize the scale of positive externalities of the entire regional industrial system; finally, the performance evaluation indicator is constructed to evaluate the performance of government fiscal expenditure for energy conservation and environmental protection in Shandong Province and typical municipal governments. The paper draws several conclusions: It is reasonable to use the internalization degree of positive externalities as the performance evaluation key indicator of government fiscal expenditure for energy conservation and environmental protection; there is a problem of low performance in regulating the positive externalities of enterprises in Shandong Province; the performance level can be improved by adjusting the expenditure structure of energy conservation and environmental protection funds; environmental values of unit pollutant emission reduction and unit resource conservation have obvious spatial differences, which has a significant impact on fiscal expenditure performance for energy conservation and environmental protection.