In order to measure the resonance wavelength of plasma grating, the sensitivity of grating parameters to stress is studied, a new type of stress-sensitive polydimethylsiloxane (PDMS) thin film plasma grating is proposed. Based on the principle of finite difference time domain (FDTD), a simulation model of periodic plasma grating structure is established. With the help of periodic boundary conditions, by applying stress to the grating and changing the parameters of the plasma grating (i.e. period, duty cycle and Au film thickness) to achieve the measurement of the resonance wavelength, the sensitivity of the grating parameters to the force is studied; and compare the simulation result with the theoretical value to get the relative error. The relative error is calculated by comparing the simulation result with the theoretical value. The results show that when the grating period is 0.7 μm, the duty cycle is 55%, and the gold film thickness is 0.02 μm, the response to force is most sensitive at this time; Secondly, comparing the resonance peak wavelength at different periods obtained by simulation with the theoretical calculation value, the results of the two are consistent; When the period is 0.7 μm, the wavelength of the resonance peak is 1.251 μm, and the relative error obtained by theory and simulation is less than 2%, and the result is more accurate. This method plays an important role in the fields of monochromator, spectrometer and sensor.