In a narrow sense,public goods are non-competitive and non-exclusive goods,while in a broad sense,public goods are non-competitive or non-exclusive goods including pure public goods,club goods and pool resources .Such issues as free-riding,exclusive cost,tragedy of the commons,financing and allocating have been considered as the issues of public goods in a broad sense by Samuelson,Buchanan and Ostrom,who have already built up their own classic theories of publicgoods based on different publicgoods andeconomicissues,such as pure theoryof public goods,club theoryand theoryof thecommons .Recent researches on publicgoodsin general have shifted to the issue of supply,governmental supply,private supply,joint supply,voluntary general supply andanycombination of which are the basic supply modes .Studies on theseaspects have also shown that future researches on public goods might mainly focus on the combination of ecological economics,spatial economics or welfare economics with public goods theory.