The paper introduces the structure and working principle of modular multilevel inverter, according to the characteristics of modular multilevel inverter and its application in the highvoltage and highpower, the capacitor voltagesharing control algorithm based on sorting method combined nearest level modulation are applied to achieve the capacitor voltage balance and the stability of the system. Then, a simulation inverter model of 7 level is built by MatlabSimulink using the above mentioned control strategy. The module capacitance voltage fluctuation and the harmonic distortion rate of f inverter output voltage and current have been analyzed to show that the inverter output waveform is of high quality, has less harmonic content, capacitor voltage fluctuation for SM is small and verify the rationality and validity of capacitor voltagesharing control strategy and nearest level modulation strategy.