The DC modular photovoltaic power generation system, which is composed of a large number of PV DC modules and the central inverter module, has the advantages of flexible installation and convenient maintenance. It also effectively solves the problem of heat spot effect and power mismatch of photovoltaic cells, and improves the efficiency of photovoltaic cells. It is suitable for building integrated photovoltaic. This paper employs an isolated full bridge topology as the integrated DC-DC converter in the photovoltaic DC building module, analyzes the working principle of the DC modular photovoltaic grid connected system, studies the parallel connection of the multi DC modules, and puts forward the control strategy. Finally, the prototype and simulation model of DC modular photovoltaic grid-connected system are constructed to verify the feasibility of the system and control.