Organic solar cell (OSC) with an inverted structure based on subphthalocyanine (SubPc)/C60 is fabricated by using Cs2CO3, graphene:Cs2CO3 mixed system and ZnO nanoparticles as cathode modifying materials, and its influences on the performance and stability of OSC are investigated. The results show that the OSC with an appropriate thickness of cathode modifying layer exhibits higher performance and it is more stable than those unmodified ones. The power conversion efficiency (PCE) of the Cs2CO3 and graphene:Cs2CO3 mixed material modified device is enhanced by a factor of two. Meanwhile, the ZnO nanoparticle modified device shows a highest open-circuit voltage (VOC) of 0.89 V, and the PCE increases more than 4 times. Besides, the adoptions of different cathode modifying materials and the inverted structures can effectively prevent the series resistance of the device from increasing, thereby improving the stability of the device.