In order to solve the problem that the fish belly is easy to scratch by the existing dirt-removing device , a kind of dirt-removing device for freshwater fish with reciprocating operation is designed. Taking carp as the test object, a sensory evaluation model of dirt-removing effect was established with visceral removal degree and fish belly integrity degree as evaluation indexes. The influences of process parameters such as starting position, feed speed and feed quantity of reciprocating operation of dirt-removing tool on dirt-removing effects were analyzed, and the process parameters were also optimized. By increasing the starting position and feeding rate, decreasing the feeding rate were beneficial to the improvement of the degree of internal organs removal, but the possibility of abdominal injury was increased. The order of influence of process parameters on the comprehensive effects of dirt-removal was operational speed >feed rate> starting point. When the starting position was 27 mm, the feed rate was 0.23 m/s, and the feed rate was 64 mm, the internal organs removal degree and the fish abdomen integrity degree score were 4.65 and 4.82, respectively. The comprehensive dirt-removal effect of this scheme was the best.