Mesocyclone occurred in supercell,squall line and the merge of island echo and band echo were detected and analyzed. The mesocyclone occurred in supercell has long lifeline.Going with the mesocyclone hail occurred. When the base of mesocyclone was near surface ,hazard wind occurred. If the base of mesocyclone was high above surface ,hazard wind would not occur. The cause of the meso is the strong upward inflow and located at the V-notch. The mesocyclone occurred in squall lifeline has a short lifeline. But when the mesocyclone occurred ,the strong wind occurred. The cause of the meso is the jet stream and located at the frank of the jet stream. The mesocyclone occurred in the merge of island echo and band echo has a short lifeline. When it occurred, hail and hazard wind and heavy precipitation occurred. The cause of the meso is the two stream in opposite direction and located at the place the two echo merged.