A complete statistical study is made for all magnetic storms reported by Beijing observatory during 1979 to 2000. It includes occurrence dependence on type of the storm, intensity of the storm, and time (year, season, and month). A comparison between the occurrence and the number of sunspots is also carried out. Further statistical analysis for part of the great magnetic storms shows that there are obvious differences between activity level represented by Beijing observatory and that by Dst. Such differences depend upon local time of Beijing (BLT). Cubic polynomial fitting results show that the activity level is lower at dawn and higher at dusk in Beijing than that represented by Dst, and the difference between dusk and dawn is about 63% of Dst.