Abstract: Under the background of rendezvous and docking of vehicles in the approach phase in space, an equivalent mechanical model for liquid sloshing under zerogravity and microgravity is investigated. Based on the model built in automatic transfer vehicle (ATV), a springmass equivalent mechanical model applicable to liquid in spherical tanks under zero/microgravity is proposed. Parameters of this model are obtained by combining the method of parameter identification through CFD computation with traditional modeling method used for liquid sloshing in normal gravity. In this paper, introduction to this model is given first, then the approach to parameters of this model is described, and solution equations for slosh forces and moments are derived based on the principle of virtue power. Feasibility and accuracy of this modeling method are analyzed by comparing the slosh forces and moments to results of the computational fluid dynamics (CFD) software Flow3d.