The silver carp was used to study mechanical characteristics of cutting fish head.The head-cutting machine of freshwater fish was designed to provide an important theoretical basis.Statistical analyses of basic signs parameters of the head of the fish body including length,width and thickness were made to determine the freshwater fish head orientation and to snout the fish head to fish back line for locating datum.To determine the shear force,the important factors affecting the shear effect of freshwater fish head-cutting including fish refrigerating time,the sliding cutting angle,placement of fish were studied with the orthogonal experiment.Results showed that the optimal condition for freshwater fish head-cutting was that fish was horizontally placed after 6 h frozen.The thickness of curved cutting knife used is 2.0 mm.At this time to has The minimum shear force of head-cutting was 186.7 N under the optimal condition.The surface level of fish head-cutting was smooth.There was no obvious defect of fish flesh with head-cutting.