The invention relates to a fish opening gutting device. The gutting effect of the prior art is limited, for example, small intestines or mucous membranes which are connected with guts cannot be thoroughly cleared only by the way of water spraying, so the thorough gutting effect cannot be reached. The fish opening gutting device comprises a circular knife, a raw material conveying mechanism and a driving mechanism, wherein the circular knife comprises a spiral arc knife, a triangular sharp knife, a toothed gutting device, a brush-type brushing device, a water spraying assembly and a transmission mechanism, the circular knife is arranged on a transmission bracket of the transmission mechanism, the transmission bracket of the transmission mechanism is arranged below a transmission chain of the raw material conveying mechanism, and one end of the transmission bracket is fixed on a board of the fish opening gutting device through a fixed seat; and the driving mechanism is respectively connected with a main transmission shaft of the transmission mechanism and a transmission shaft of the raw material conveying mechanism. The guts are sequentially removed, and then the fish can be washed through the water sprayed by the high-pressure water spraying assembly on the end of a handle, so the opening and the gutting functions are faster to realize by the fish opening gutting device and the fish opening gutting device can thoroughly clean the fish.