In order to improve the efficiency of fish cutting and processing, the qualified rate of products, and reduce the labor cost, this paper explored a kind of mackerel fillets water jet cutting technology.With frozen mackerel fillet as raw material, the second-class spacing was performed by water knife cutting after thawed. The cutting rate, fish loss rate and sensory value of the cutting surface were used as evaluation indexes, and the thickness, water knife pressure and water knife action time were used as process parameters. The multi-index comprehensive scoring method was used to evaluate the cutting effect of mackerel mackerel fillet.The water jet cutting technology of mackerel fillet was optimized by single factor and orthogonal test.The results showed that with the increase of fish fillet thickness, the cutting rate and sensory value of cutting surface decreased, and the loss of fish meat decreased first and then increased; With the increase of water jet pressure and water jet action time, the cutting rate increases, the fish loss rate decreased, and the sensory value of the cutting surface first increased and then decreased.The optimum water jet cutting technology for mackerel fillet was as follows: fillet thickness was 13 mm, water knife pressure was 50 Mpa, and water knife action time was 2.0 s. Under these conditions, the cutting rate of mackerel fillet was 99.8%, the fish loss rate was 0.133 %, the sensory value of cutting surface was 8.5 points, and the overall cutting effect score was 99.5 points.