The invention presents a middle-sized low-speed permanent magnetic direct drive wind turbine generator and a parameter self-study control method thereof, and belongs to the technical field of wind power. The low-speed permanent magnetic direct drive wind turbine generator structure (shown as Figure 1) comprises a wind wheel-1, a main shaft-2, a main bearing base-3, a main frame-4, a low-speed disk type permanent magnet motor-5, a low-speed shaft brake-6, a variable pitch dragging system-7, a yaw dragging system-8, and a cabin cover-9. The wind turbine generator controls the running by a parameter self-study algorithm, and applies a BP neutral network to predict the control parameter pitch angle beta, rotate speed omega, torque q and power p of the control system, determines the control objective through the prediction value, and completes the speed change and the bending moment control. Compared with the traditional low-speed disk type permanent magnetic wind turbine generator, the middle-sized low-speed permanent magnetic direct drive wind turbine generator reduces the risk that the power generation is slipped down and even cannot generate power for the demagnetization caused by shock of the permanent magnetic motor, and decreases the main shaft and other bearing parts; the main frame can apply a lightweight welding structure, so that the production cost is reduced and the generator is simple to maintain.