Based on the theory of H-bridge multilevel converter, the structure of a three phase cascaded multilevel inverter (LVCMI) and its control strategy are proposed in this paper. Several standard three-phase bridges can be reconnected into a new single three-phase bridge at ac-side. Simulation results show that such topological structure can increase the output voltage capacity and reduce the THD. It can be used as an inverter or rectifier in three phase system. In theory, it can be cascaded unlimitedly. The more cascaded, the higher output voltage and the lower THD. Experimental results of LVCMI with 3-module verified the feasibility of the proposed inverter.