This paper built a simulation system of Public Goods Experiment to study the Conditional Cooperation. The study of this paper was divided into 3 parts including the execution of Public Goods Experiment in laboratory, the BPNN (Back Propagation Neural Networks) modeling of the resulting data of the former experiments and finally the developing of a simulation system of Public Goods Experiment. The results of the simulation show that displaying the number and name of people who have endowed to the Public Goods Pool instantly is the best condition for stimulating Conditional Cooperation which also means the best information displaying condition of avoiding free riders.