Based on the relationship between the refractive index and the pressure of gasthe dynamic pressure of gas can be measured non-contact by laser interferometer. At the same timethe influence of temperature on the measurement of gas dynamic pressure by laser interferometry was studied. The virial expansion of gas equation of state was carried out from the angle of quantum mechanicsand the model of gas pressure and refractive index was established. Based on the latest correction of Edlen equationthe influence of temperature on the measurement of gas dynamic pressure by laser interferometry is explored. The results show that when the pressure is constant in the low pressure rangethe temperature change in the range of -20~80℃ is inversely proportional to the refractive index of the gasand the change of the refractive index is about 10-6/℃. The temperature change of 1℃ is equivalent to the pressure 311.47Pa. The temperature change has a great influence on the measurement of gas at low pressure. It should be ensured that the temperature control is better than ±0.05℃so as to meet the requirements of dynamic pressure measurement by laser interferometry.