The present invention provides a DC voltage compensation method of a parallel hybrid multi-level inverter. The inverter is a three-phase power transmission structure which is formed by the series connection of parallel single-phase structures. Each of the parallel single-phase structures is formed by an H-bridge full control device structure and a sub-module cascade structure in parallel connection. The H-bridge full control device structure is formed by the cascade structures of four full control devices. The sub-module cascade structure is formed by the series connection of half-bridge sub modules. The compensation method comprises the steps of adding an isolation time in an inverter normal operation mode process and freely controlling the sub-module cascade structure in the isolation time to output needed compensation voltage, the compensation of DC voltage vacancy is realized, and the three-phase distribution proportion is adjusted according to needs by the compensation proportion in the three-phase power transmission structure. Through the method provided by the invention, the DC voltage fluctuation compensation of a parallel hybrid new topology can be effectively realized, and the method is especially suitable for the voltage compensation under an AC system failure.