Si_xN_y is often used as the suppression material of quantum well intermixing (QWI). In order to explore the effect of Si_xN_y growth process on the intermixing effect of InGaAs/GaAs quantum well structure, a series of experiments are carried out on the process parameters of plasma enhanced chemical vapor deposition (PECVD) method, such as deposition time, SiH₄ flow rate, and radio frequency (RF) power. The experimental results show that Si_xN_y can protect the quantum well well, but its thickness has little effect on the inhibition effect of QWI. When the SiH₄ flow rate is large, Si is rich in Si_xN_y, and Si may diffuse during annealing to form electrical compensation with P-type ohmic contact layer, and at the same time induce quantum well intermixing, resulting in a large blue shift of its wavelength. With the decreases of SiH₄ flow rate, the content of Si in Si_xN_y decreases, and the refractive index decreases, but the blue shift is still large. In a certain range, the blue shift increases with the increase of RF power, and when the RF power is 50 W and the SiH₄ flow rate is 50 sccm, Si_xN_y plays a better in quantum well protection, and the blue shift is only 14.1 nm.