Self-cleaning method of surface cleaning machine

The invention belongs to the technical field of cleaning equipment, and particularly provides a self-cleaning method of a surface cleaning machine, the surface cleaning machine comprises a cleaning roller driven by a driving motor, a dirt suction device driven by a dirt suction motor and a liquid supply device, and the dirt suction device comprises a dirt suction port, a dirt containing barrel and a dirt suction pipeline connecting the dirt containing barrel and the dirt suction port. The self-cleaning method comprises the following steps: step A, a cleaning roller cleaning stage; step B, a dirt suction stage; c, a stage of cleaning the sewage suction pipeline: the sewage suction motor is started, the suction power of the sewage suction motor is P1, P1 is larger than or equal to 0.3 P and smaller than 0.5 P, the sewage suction device sucks the cleaning liquid into the sewage suction pipeline through the sewage suction opening, the cleaning liquid flows up and down in the sewage suction pipeline to continuousl