The present disclosure provides a flushing device and method for an evaporator of dryer, and a dryer. The flushing device comprises an evaporator, a water storage box and a condensate water pan for collecting condensate water, wherein an eccentric bucket is arranged between the water storage box and the evaporator, a supporting structure is arranged at two symmetrical sides of a periphery of the eccentric bucket, the supporting structure enables the eccentric bucket to turn over along with a change in the center of gravity of the eccentric bucket, a pipeline for conveying condensate water to the eccentric bucket is arranged between the eccentric bucket and the condensate water pan, an opening of the eccentric bucket is arranged upwards, and after the eccentric bucket is turned over, the opening of the eccentric bucket is aligned with the evaporator, such that condensate water in the eccentric bucket flushes the evaporator.