With the steady progress of China's dual carbon goal, the proportion of photovoltaic (PV) power generation is rising rapidly, while PV is greatly affected by the topology of power electronic converter, output power quality and working efficiency. Based on this, this paper proposes a PV power Conversion System (PPCS) based on IHBMLI (Improved H-Bridge Multilevel Inverter). The power generation system can realize the efficient utilization of solar energy, the total harmonic distortion can be greatly reduced through the five-level output voltage, and the low switching frequency reduces the total loss of the system, so as to improve the power quality of the distribution system. In addition, a single input multiple output (SEPIC) converter is designed to track the MAXIMUM power point of PV to achieve isolation from dc source. Finally, the performance of the proposed inverter is verified by simulation and experiment. The results show that the power factor correction can be realized through the reactive power support and harmonic suppression of the power grid, and the performance of the converter in terms of output power quality and efficiency can be effectively improved.