In this study,we analyze several calculation methods of the production rate of methane in rubbish and make a detailed calculation of the production rate and the cumulate output of methane. On the basis of this study,we use a real rubbish dumping field to calculate the production rate and the cumulate output of methane. It helps to supply the useful reference deta for producing electricity from rubbish in the rubbish dumping fields. Finally we calculate the methane output from rubbish of every province and the potential methane resource in rubbish of the whole country.