Three-level inverters could achieve more levels of output voltages with lower total harmonic distortion (THD). However, increasing of semiconductors would decrease the reliability of the inverter, what’s more, the topology causes a low frequency oscillation of the neutral-point voltage. This paper establishes an improved three-level inverter topology, it has better fault-tolerant ability to work as a two-level inverter by its asymmetry topology, when a break occurred in any of devices. In addition, the improved topology adding assistant leg to control neutral-point voltage independently. On the basis of the improved topology, a more accurate mixed logic dynamic model (MLD) is established for the inverter, then the MLD model is taken as prediction model to research the finite control set model predictive control (FCS-MPC) for the inverter. The paper explicitly researches the solving algorithm and realization procedure of the inverter, its feasibility and validity is verified by the simulation and experiment. This work is supported by National Basic Research Program of China (973 Program) (No. 2015CB755800).