In InGaN/GaN multiple quantum well (MQW), the quantum-confined Stark effect (QCSE) induced by a strong piezoelectric polarization field decreases the electron-hole radiative recombination rate. We design and grow the MQW structure with an InGaN strained-layer to reduce the polarization field, and carry out the photoluminescence spectrum experiment with variable temperature and variable excitation intensity, the results indicate that the MQW internal quantum efficiency is increased by inserting an InGaN strained-layer.The analysis of the peak energy blue-shift shows that the strain-layer effectively weakens the QCSE and obviously increases the peak intensity of the corresponding electroluminescence spectrum. This verifies that the InGaN strained insertion layer has the effect of which is beneficial to improve the luminous efficiency of MQW and the performance of the device.