Abstract: Based on waveform data recorded by 108 broadband seismic stations of the Digital Seismic Network in Inner Mongolia Autonomous Region and neighboring provinces during period of 2014—2018, the magnitude of 85 earthquakes were computed by using the rapid determination method and the conventional determination method, at the same time, the magnitude deviation of the two methods were measured and the magnitude correction is given, in the end, the results of the two methods were compared. The results show that: ① The magnitudes calculated by the rapid determination method is smaller than that calculated by conventional determination method, the absolute magnitude deviation range between 0 and 0.5, the mean value of magnitude deviation is 0.25. Using Gauss curve fitting, it is indicated that the distribution of magnitude deviation is still the Gaussian's's. ② Measuring time of magnitude which is determined by amplitude is given, the time using rapid determination method is 0.6 times that using conventional determination method. On average, It'd probably cut that time by 90 minutes, and it will reduce the time on quick report. ③ The rapid determination method is not recommended for small earthquakes, which of S-wave does not develop well for vertical component. ④ It may diminish the influence of magnitude deviation to the fast determination of earthquake parameters and improve the magnitude determination accuracy in Inner Mongolia Digital Seismic Network. This method may provide a reliable reference basis for rapid determination of standard magnitude.