The invention relates to the technical field of metal waste treatment, in particular to a method for recovering regenerated nickel sulfate from nickel-plated tank slag and sludge. The nickel-plated tank slag and the sludge serve as a raw material, working procedures of dissolution leaching, pressure filtration separation, complexation removing of Fe and As, extraction and impurity removing, ultrasonic oil removing and concentration drying are conducted, in the working procedure of ultrasonic oil removing, ultrasonic oil removing is conducted by adding composite activated carbon which is prepared by means of the method that nano-modified activated carbon is subjected to modification of hydroxypropyl-beta-cyclodextrin, and oil contamination in a solution can be effectively removed through combination of the composite activated carbon and ultrasonic waves. According to the method for recovering the regenerated nickel sulfate from the nickel-plated tank slag and the sludge, the technological process is simple, operation is convenient, the metal recovering utilization rate is high, waste water discharging is little, nickel sulfate which is high in regeneration purity and accords with the national standard can be recovered, the method can be widely applied to industries of electroplating and batteries, and the method has good economical benefits.