In this paper, the sloshing of liquid in a spherical tank with spacer is investigated under low-gravity conditions. Unsing the method which concerning a kind of charateristic functions, expanded into polynominal expressions, the free and forced-sloshing problems are solved. The natural frequencies of liquid sloshing are obtained. The equivalent mechanical models of liquid sloshing are given. The moment and force of liquid acting on tank wall are derived. The numerical results are compared with the ones of spherical tank without spacer, and the advantages of spacer are shown.