Abstract: Public resources are the parts that owners have to give up, or the parts whose property rights has not been successfully defined when trading. The process of property rights defying naturally is solving the benefit problem to public resources between both sides or within economic units, so that public resources determines property rights evaluation. The writers divided public resources into two types—the inner and outer public resources. Then the writers proved the relationship among different property rights types, and the optimum way of selecting property rights, through model analysis. The writers' conclusion is that trade costs and production costs are the basic element to property rights definition ; and contests to public resources make all different types of property rights form a integrated series—from one pure common property rights(resources without sacristy) to the other pure common property rights(no resource can be used);Pure ownership (without trade) is particular form, while club and private property rights are the intergradations in the series; Real property rights selection depend on game equilibrium structure between economic units.

Key words: public domain, property rights, property rights definition, transaction costs