For the difficulty on spacecraft ground simulation of high precision microgravity, a vertical weightless movement method based on equivalent dynamics was proposed. The equivalent dynamics and its conditions were brought forward to implement high precision vertical weightless movement simulation. Then, the simulator design requirements based on the proposed method were analyzed. Through simulation analysis of the simulation accuracy, the possible problems of the design principle were discussed. Error analysis and simulation calculation results show the weightlessness simulation accuracy is up to 99%,which can satisfy the requirements of the high precision microgravity simulation experiment.