The invention provides a direct torque control method for a permanent magnet synchronous generator. The direct torque control method comprises the steps that a nonlinear mathematical model of the permanent magnet synchronous generator in a coordinate system is built; a PI controller of a rotational speed control ring is designed, operation is conducted on a rotational speed instruction value and an actual measurement rotational speed value through the PI controller, and an instruction value of inner ring electromagnetic torque is obtained; a state equation with stator flux linkage amplitude and electromagnetic torque amplitude of the permanent magnet synchronous generator serving as state variables is built; a permanent magnet synchronous generator inverse system expression of a permanent magnet synchronous generator original system is worked out; a new pseudo-linear system is built; an equivalent linear subsystem of the pseudo-linear system is worked out; a sliding mode variable structure control law of the equivalent linear subsystem is designed through a variable exponent reaching law; the sliding mode variable structure control law is substituted into the inverse system expression, and a controlled quantity of the original system is obtained through inverse solution. According to the direct torque control method for the permanent magnet synchronous generator, linear decoupling control over the electromagnetic torque amplitude and the stator flux linkage amplitude in direct torque control of the permanent magnet synchronous generator is realized, and robustness of a whole system is high.