The non-contact measurement of gas pressure is an important research direction in the application of laser technology. In order to solve the problem of traceability in the process of gas pressure measurement, a pressure measurement method based on laser interference technology is designed. Through the theoretical research of the Lorentz-Lorenz equation, the gas state equation and the optical path difference equation, a pressure measurement model based on the optical path difference is established, and the pressure measurement problem is traced back to the optical path difference. With CO2 as the research object, a pressure measurement experiment system was built to carry out pressure measurement experiments with a pressure range of 1~3atm under the conditions of 293K, 313K, and 333K. The experimental results show that the pressure measurement value is in good agreement with the actual value, and the relative error is within 5%, which proves the correctness of the pressure measurement traceability model.