To solve the problem of inaccurate Poisson's ratio in the design of asphalt pavement structures, based on the theory of complex modulus and linear viscoelasticity, the indirect tensile test was used to calculate and analyze Poisson’s ratio of asphalt mixtures. Furthermore, the test parameters and operational considerations of the indirect tensile test were clarified, and the conditions for judging whether the displacement derivative reaches stability under each test temperature were proposed. The indirect tensile test was carried out on five types of asphalt mixtures to analyze the effect of different asphalt and different mix grading types on Poisson's ratio, and the recommended values of Poisson's ratio for AC asphalt mixtures were proposed. The results of the study show that: the influence of temperature and loading frequency on Poisson’s ratio of AH-70 asphalt mixture is very obvious, showing that as the temperature increases and the frequency decreases, Poisson’s ratio gradually increases; its variation range is basically between 0.1 and 0.5, and with the increase of the mixture particle size, this variation range tends to decrease. Poisson’s ratio of SBS-modified asphalt mixtures is less affected by temperature changes and Poisson's ratio variation range is smaller, but at each frequency at each temperature, Poisson’s ratio changes with frequency are also more obvious. Under standard test conditions (20 °C, 10 Hz), Poisson’s ratio ranges from 0.20 to 0.35 when using AH-70 bitumen, with a recommended value of 0.28; when using SBS modified bitumen, Poisson’s ratio ranges from 0.15 to 0.30, with a recommended value of 0.23.