Abstract: Base on optimization theory,effectiveness standpoint,and the resource disposition theory to explore the private supply kept inside the public goods,it was proposed that the provision of public goods(as Qinba Mountainous area water supply project here) supplied according to integral optimization was greater than the balanced supply of public goods by Nash equilibrium theory,i.e.,it was meant that the water quantity provided by joint decision-making of Qin and Ba mountainous areas was greater than that of provided by individual decision making,It was indicated that more efforts should be made to reduce water pollution.Similarly,the result out of joint game was different from the independent game based on the minimized cost target,it was proposed that the joint game would optimize the overall welfare in the two corresponding mountainous areas.