Getting the accurate damping rates has long been an intractable problem for spacecraft control system modeling.In the present paper,the fundamental eigenfrequencies and damping rates of liquid sloshing with small amplitude in a circular cylindrical tank with a spherical bottom were studied in the experimental way.And the results were compared with the numerical values of FEM obtained by the authors in the previous research.The numerical values of frequencies are close to the experimental results,and the numerical values of damping rates in the case of clean surface are smaller than the experimental value.If the damping of contaminated free surface is introduced to the FEM computation by a factor,then the numerical values of damping rates can approximate to the experimental results.This kind of fuel tank is popular in some satellite series,so the results of the paper could be referenced for a practical engineering task.