Abstract: In order to measure the liquidlevel of propellant in tank with ultrasonic echo measurement method, one of the key problems is to study the effect of temperature on the propagating velocity of ultrasonic wave. Based on the physical and chemical characteristics of propellant, experiment was designed to establish the velocitytemperature model of propellant. Then the models of unsymmetrical dimethylhydrazine(UDMH) and nitric acid were obtained by using regression analysis, and the models accuracy was analyzed.