The enhanced internal quantum efficiency of InGaN/GaN multiple-quantum-wells (MQWs) structure is demonstrated by paving the graphene layers on the MQWs surface. Compared to the conventional MQWs, the internal quantum efficiency of the graphene/InGaN MQWs hybrid structure exhibits a remarkable 2-fold increase. The high charge carrier density in graphene layer is accounted for the enhanced internal quantum efficiency. Moreover, the negligible photoluminescence emission peak shift with increasing the excitation power as well as the decrease of radiative recombination lifetime are attributed to the reduced quantum-confined Stark effect, which correlates to the screening of the polarization field in the c-plane nitride-based quantum well structure.