Recently there occurred crowd stampede accidents frequently all over the world，where some caused serious casualties. Metro station is a spot tending to incur crowd stampede，therefore it is of great theoretical and practical significance to early-warn the crowd stampede in metro station and take effective evacuation policies. This paper takes Beijing Metro Station as a case referred to the status quo and problems of crowd stampede risk control，to construct a risk early-warning framework of metro station crowd stampede based on video analysis，proposes a so-called 3-pre principle including pre-control，pre-warning and protocol，to propose a 2-stage evacuation model，to conduct a simulation，and to put forward policies of metro station crowd evacuation.