Liquid reservation and liquid-gas separation system is an important factor in a thermal control system and an environmental control system of spacecraft. A surface tension tank is one of the important device in the system. A functional model and partial models were fabricated and their behavior verification tests were conducted under the microgravity.The experiment was conducted in NASA KC-135 reduced gravity plane in 1991 January.Expelling function was verified with a functional model. The tank has channels with fine mesh screen and expels liquid only. The expelled distilled water is returned into the tank again, the ratio of liquid to gas is kept constant, and the flow rate of the discharged water is a parameter. The liquid behavior was recorded on video tape and acceleration data was recorded on a data recorder. As a result liquid-gas separation was perfectly achieved in any phase of the parabolic flight, namely under the high-G to micro-G environment, and it was verified that the functional model has the required function.In the partial model experiment, four transparent acrylic spherical tanks were prepared. They had some imitation structures as essential parts of the surface tension tank inside and were half-filled with water. The liquid behaviors were recorded on video tape. By the analysis of video, useful data about behaviors of liquid around imitation channels and fine mesh screen surface was obtained for tank designing.