Abstract: According to the theoretical relationship between wave velocity and surface tension，we design the experiment in a range of temperature and analyze the experimental results. The U - tubes we applied in the experiment are self-made ones. We measure the surface tension of the liquid and video the process of the liquid transition. The specialty of this process is the footage of the clock，which we also video during the experiment. If one displays our video on computer by each frame，one will see the peak of the wave and the exact time simultaneously. If one divides the distance of the peak movement with time，one can get the speed of the waves. An involved method is compared with the traditional ones in this experiment，the new method makes the experiment easier in process and precise in measurement.

Key words: U-shaped tube, surface tension, video recording, wave velocity measurement