Abstract: Aiming at the low reliability of the photovoltaic（PV）DC-DC converter series system,this paper presents a series system scheme based on redundancy of N-M PV DC/DC converter,analyzes the operation characteristics and control strategy of the series system,and studies the reliability of the N-M series system. The research results show that the redundancy series system scheme of N-M PV DC-DC converter can effectively improve the operation reliability of the series system. The simulation model and experimental platform of the series system are built,and the feasibility of the proposed N-M PV DC/DC converter series system is verified by simulation and experimental results.