Abstract: Traditional Arps production decline analysis method requires to determine the initial time, production and decline ratio before analyzing. Owing to the difficulty for determining these factors in actual operation, the results obtained from this method are often cluestionable. This paper presents the diagnosis method for production decline laws, by which it is very easy to determine the model parameters of the production decline laws.Through choosing referential time, production and decline ratio, this method is more flexible, simple and practical than the Arps method in terms of analyzing the production decline.