InGaN-based photovoltaics (PV) devices have attracted great attentions because of the excellent photoelectric performance over the past decades. The photocurrent of the InGaN/GaN MQWs solar cells could be further improved by coupling plasmonic with piezo-phototronic effect. Here, we fabricated an InGaN/GaN MQWs solar cells with Ag nanoparticles and the short circuit current of the solar cell was improved by 40% with a static external strain applied. The transmission spectrum and the electromagnetic field distributions of the nanoparticles array were simulated with a finite element analysis model. The physical mechanism for light absorption enhancement by the coupling effect in the quantum well structures was illuminated through a self-consistent numerical calculation with non-linear piezoelectricity polarization. This work demonstrated the coupling between the plasmonic and piezo-phototronic effect achieves significant increase in InGaN/GaN MQWs solar cell power conversion efficiency without any complicated process involved.