Abstract: For Surface Acoustic Wave (SAW) pressure sensor based on Langasite (LGS), a multi-parameter decoupling method of the pressure and temperature interference is proposed. Theoretically, frequency response in different temperature and pressure is calculated by the method which combines Finite Element Method (FEM) and the perturbation theory. Taking a SAW pressure sensor based on (0°, 0°, 100°) LGS substrate with point load structure as an example, the parameters of the decoupled formula is calculated. The experiment is carried out under a temperature scope of -55℃-125℃and a pressure scope of 0- 1 MPa. The experimental frequency response coincides with the theoretical result, which shows a reasonability of the decoupling method.