This paper use Kantian Maxim of Laffont (1975)、Bordignon (1990) and Bilodeau and Gravel (2004) on the game in which firms spontaneously prevent or control pollution was set to understand how the voluntary agreement influences the behaviors of firms. The results proved that voluntary agreement makes firms agree with the moral restraint of firm interaction, Kantian Maxim, which meets the same moral evaluation and ration assumption. In Kantian Maxim, all firms provide Lindahl equilibrium quantity and Pareto efficiency solution.