Abstract: Sloshing of liquid propellant in microgravity and its influence on the attitude control system have been studied for several decades. Accurate modeling is necessary, especially, for modern spacecrafts carrying large amounts of liquid propellant. Research progress on this issue is reviewed, including a summary of analytical methods for both linear and nonlinear sloshing, an introduction of numerical techniques such as modal analysis and CFD (computational fluid dynamics) methods, and also a description of experimental approaches and advances. Finally, some critical problems concerning liquid sloshing in microgravity are proposed and discussed.