The utility model provides a three-layer reducingcasing coupling thorn fishing net. A three-layer fan-shaped fishing net provided with a middle mesh and a side mesh is connected under a head rope, and the lower part of the fishing net is connected with net sinkers. The dimension proportion of the upper end to the lower end of the fishing net is 0.5:1.5, the upper end and lower end reducingcasing coupling rate of the fishing net is 30 percent, and the proportion of the middle mesh to the side mesh is 1:2. The fishing net provided by the utility model adopts the three-layer arrangement, the resistance is small, in addition, through the head rope net reduction, the fishing net is in a fan shape, the condition and is favorable for fish seining, in addition, small fish and small aquatic organisms can be favorably given up, and the water body ecological environment can be favorably protected. The three-layer reducingcasing coupling thorn fishing net is suitable for being used as a fish catching net.