To enhance the survival capability and fast reaction capability of missile weapon system, study on the load to ground during the process of missile erection has been carried out. The bearing load of launching site is analyzed in missile erecting process with the hypothesis that the launching vehicle is bilateral symmetry object, and jack reaction force in erecting process is calculated while the influence of wind load is considered, which provides load criterion for building evaluation model of launching site. The running curve of jack reaction force related to erecting angle is yielded through using pressure data acquisition system, and the data acquisition result is analyzed with real measuring data. The analyzed result shows that amplitude and variation trend of jacks reaction force are in well match with theoretical calculation results, and the computation result is rational, which can offer references for selecting and judging intensity of missile launching site when unsupported random launching way is applied.