Abstract: The analytical velocity potential and the wave height of the sloshing liquid with horizontal hydro-static surface are obtained from Laplace equations. It is observed experimentally that the mode shapes of a curved hydrostatic surface in a microgravity condition do not appreciably differ from the mode shapes of a flat hydrostatic surface. To obtain sloshing characteristics in cylindrical containers in microgravity conditions, the mode shapes of a flat hydrostatic surface are used to approximate the curved hydrostatic surface. After truncating the first five modes of sloshing, the dimensionless coupling dynamics equations for the sloshing liquid and the main rigid body are derived by the Lagrange equation. The bifurcations of the sloshing modes are simulated for the amplitude and the frequency of the force variations. The effects of the system parameters, such as the Bond number, the contact angle, the contact angle hysteresis, the liquid height, the frequency ratio, and the mass ratio, and of the periodic form and the direction of the force, on the bifurcations of sloshing modes are studied.