A noise reduction method of a ventilator, comprising the following steps: S1 starting a ventilator and imputing a required wind pressure d at a man-machine interface, and then sending a signal to an actuator through a processor, and adjusting a first blade automatically to a maximum adjustable angle state a′° through the actuator and a second blade to a minimum adjustable angle state b°; S2 regulating a revolution speed, when a wind pressure is d, feeding back a revolution speed c, a conducting noise e1 and a radiated noise f1 to the processor through an acquisition device, and after the processor receives a revolution speed information, sending a command to lock the revolution speed to the actuator through the processor. The present disclosure can effectively solve the poor noise reduction function of the present noise reduction hoop, and can effectively reduce the cost and simplify the installation process.