The oscillation of liquid/gas free surface in a partially filled storage tank caused by an abrupt drop of gravity level is of critical importance for the fluids management in space. In present study we investigate the dynamic behavior of free surface in tank models (tubes) using water as the working medium utilizing the Drop Tower Beijing, which can provide a 3.6s short-term microgravity condition. Meanwhile, the corresponding numerical simulation using volume of fluids (VOF) methods was carried out. It is shown that the dynamic behavior of free surface, which belongs to the typical phenomenon of capillary flow, is affected by the properties of working medium and the geometry and surface properties of the storage tank (especially the contact angle) jointly. The numerical simulation could capture the major characteristic oscillation frequency of free surface revealed by experiment. The oscillation frequency of free surface increases with the increasing air fraction and remains nearly constant at large air fraction. For the same air fraction, the oscillation frequency significantly increases with the decreasing tank diameter.