The invention discloses a purse seine trapping method based on feeding and trapping. The purse seine trapping method can effectively prevent juvenile fishes from being trapped in the trapping process.A separation device is involved. The separation device comprises a floating rack which floats on the water surface, a separation cylinder device which is arranged on the floating rack and a feeding pipe. The separation cylinder device comprises a separation net cylinder which is arranged on the floating rack, an isolation cylinder body which is located below the separation net cylinder, a floating isolation cylinder which sleeves the isolation cylinder body, an annular inflation airbag cover which sleeves the floating isolation cylinder and an air inflation pipe. The purse seine trapping method based on feeding and trapping sequentially comprises the following steps that 1, bait is put into the separation net cylinder from an upper port of the separation net cylinder; 2, bait is put intothe isolation cylinder body through the feeding pipe, then the annular inflation airbag cover is inflated through the air inflation pipe, and accordingly the floating isolation cylinder is driven to float upwards; 3, net casting and fishing are conducted in a purse seine for purse seine breeding.