According to the shortcomings of photovoltaic grid connected inverter with high failure rate, high harmonic content, and complex control, a utility method of photovoltaic grid connected with DC-synchronous motor is proposed. Photovoltaic supply power is for DC motor in this photovoltaic grid connected system, and DC motor drives synchronous motor coaxial rotation, which realizes the conversion between DC and AC power. The grid connected control system includes maximum power point tracking control, motor speed control and synchronous motor terminal voltage control. The photovoltaic grid connection can be achieved when synchronous motor meets grid conditions. When connected to grid, the output of synchronous motor varies with the output of the photovoltaic. Simulative results verify the feasibility of the method based on MATLAB/Simulink. The grid voltage and current waveform are good, and active and reactive power can be provided to improve the power factor of the grid. This work is supported by National Natural Science Foundation of China (No. 51177047).