In order to improve the test accuracy of the surface tension of high temperature liquid asphalt binders, formula of differential capillary method was derived, and the principles, methods and influencing factors for surface tension testing were explored. Results indicate that the contact angle and corrected height have a significant effect on the inner radius measurement, and the inner radius measurement has a significant effect on the test results. It is recommended to select capillaries with nominal inner radii of 010mm and 020mm for surface tension test. The test accuracy of improved method for surface tension is increased by 247% 492%. It can effectively distinguish the effect of surfactants and its dosage change on the surface tension of high temperature liquid asphalt, and provide a feasible technical approach for the measurement of surface energy parameter of high temperature liquid asphalt binders.