The invention discloses a predictive type fixed turn-off angle control method. By analyzing an inverter commutation process, a calculation formula of a turn-off angle of a DC (direct current) currentchange during the commutation period is obtained; amplitude and phase changes of each AC (alternating current) commutation voltage are considered; a DC current measured value and an AC voltage are respectively processed by a moving average filter and a second-order generalized integrator, and are used for solving a trigger angle of each converter valve; and the minimum trigger angle is taken as the output of the control of the fixed turn-off angle. By adopting the control method, the capacity of a system to withstand commutation failure can be effectively improved.