With the development of distributed photovoltaic system, the requirement of grid quality is more and more higher. As the core equipment, the performance of grid inverter directly determines the stability of the system. Compared with traditional two level inverter, three level inverter has the advantages of switch loss, high efficiency, low harmonic content and lower dv/dt. Compared with the NPC, T topological structure has the loss small, less diode quantity, less independent drive power supply. A double-stage T-type three-level topology is introduced, the dq coordinate transformation-based double closed-loop control strategy and SVPWM algorithm without trigonometric functions, as well as its DSP implementation are studied, and a neutral point imbalance suppression method is proposed. Finally, a 10 kW prototype is developed, the results show that the control algorithm is effective.