The invention relates to a drop style continuous ultrasonic cleaning method and device for small sized bearings, in particular to a method and device conducting continuous transition and drop style ultrasonic cleaning to small sized precise bearings, which belongs to the field of precise bearing cleaning. With usage of ultrasonic cleaning method, utilization of an air cylinder, a track, a cleaning fluid basin, a left drop device, a right drop device, and usage of altitude difference of an inlet and an outlet of a screwed basin equipped on the left drop device and the right drop device, bearings outside the cleaning basin for cleaning are continuously inputted into the cleaning basin to clean, the cleaned bearings are continuously outputted, and automatic transition and ultrasonic cleaning of bearing are accomplished. The cleaning device is composed of a feeding apparatus and an ultrasonic cleaning device. The feeding device is composed of an electric motor, a feeding rotation disk, a rotating shaft, and an air cylinder, a supporting plate of air cylinder, a demagnetizer, a left track, a belt pulley, a belt and a feeding support. Ultrasonic cleaning of the drop devices has the advantages of simple structure, convenient operation, low cost, and high efficiency, which is capable of increasing the usage performance and market competitive strength of medium and small sized finish products of precise bearing.