An intelligent fault diagnosis and treatment method for a speed controller main servomotor, main distributing valve and proportional valve hydraulic servo system comprises the steps that (1) a speed controller electronic control system assign initial values of k1*and K12*; (2) the speed controller electronic control system collects the guide vane opening feedback value set as Y, the guide vane opening, set as Y<set>, output by a PID module of the speed controller electronic control system, the main distributing valve position, set as M<set>, output by a guide vane opening control module of thespeed controller hydraulic servo system, the main distributing valve position feedback set as M, the proportional valve position, set as B<set>, output by a main distributing valve control output, the proportional valve position feedback set as B and other data in real time; (3) whether the absolute value of B<set> minus B is larger than a threshold value b or not is judged, if the time of the situation that the absolute value of B<set> minus B is larger than the b is kept for longer than t1, a proportional valve hydraulic servo fault is reported, and fault treatment is executed; (11) if a standby is provided and out of trouble, the standby is switched on; if the standby is faulty or no standby is provided, the generator set is switched to manual operation, and if the fault is manually cleared and the generator set is switched to the manual state, the second step is executed again. By the adoption of the intelligent fault diagnosis and treatment method for the speed controller main servomotor, main distributing valve and proportional valve hydraulic servo system, the fault of the main servomotor, main distributing valve and proportional valve hydraulic servo system can be rapidlyand accurately diagnosed, and the situation that an accident expands, so that the unit load cannot be normally adjusted, even the load fluctuates greatly, and a series of problems are caused is avoided.