The invention relates to a new method for breeding leeches through fresh water soilless net cages and belongs to the technical field of aquatic animal breeding.Top openings of the net cages are closed, the net cages are fixed to a fresh water supporting object, a certain distance is kept among the net cages, 100-500 artificial bred juveniles with the average body weight being 10 mg are thrown for each net cage bottom face area of 0.5m<2>, after the average body weight of the juveniles is larger than 500 mg, the juveniles are transferred to nets to be bred continuously, or 20-200 wild juveniles with the average body weight being 0.5-4 g are throw for each net cage bottom area of 0.5 m<2>; during breeding, main food is thrown according to the amount which is 20 times of the body weight of the leeches, the food is updated periodically, and after being bred for 60-120 days, the leeches are directly poured out and harvested.The average weight of the leeches exceeds 20 g, and the size meets the use standard of the medicinal leeches.The method is easy to operate, lands are not occupied, the food resource includes natural planktons except snails, the net openings are closed to prevent natural enemies, and the method saves cost and is high in economic benefit.