In this paper, modification on magnitude frequency relation and magnitude limit determination based on NGR and MGR （commonly used models） are studied in various seismic zones in Chinese mainland since 1970. The results indicate that the MGR model can be used to describe the nonlinear frequency relations so that the magnitude frequency relations of MGR model is more suitable to magnitude frequency relation of ML 〉3.0 earthquakes of various seismic zones in Chinese mainland. The result of the fitting high sample size of the magnitude limit determination based MGR model is accurate.[著者文摘]