The invention discloses an ultrasonic assistant hot wash device and an ultrasonic assistant hot wash method for oily sludge. In the invention, sodium dodecylbenzene sulfonate, fatty alcohol-polyoxyethylene ether and sodium carbonate are used as surfactants that are mixed equivalently to prepare a cleaning solution with concentration of 2.0g/L, and the solvent is common clean water. Hot wash parameters are set as follows: temperature: 60 DEG C, time: 30min, and rotary speed of agitator: 200r/min. Ultrasonic parameters are set as follows: time: 15min, power: 400w, and frequency: 40khz. After treatment, the crude oil recovery rate of oily sludge can reach 98.70-99.20%. The oil content of upper sump oil after treatment is 97.32-98.95%, the slag inclusion rate is 1.32-0.59% and the water content is 1.36-0.46%, so as to meet crude oil refining standard substantially. Unqualified oily sludge can be treated secondarily. The cleaning solution for cleaning can be recycled and the solid residue obtained can be used in processes such as brick making and the like.