The invention belongs to the field of aquiculture, and relates to a method for breeding crabs and controlling diseases. The method provides an original biological environment with the best surviving and growing conditions for natural crabs, and obtains high quality Chinese Eriocheir sinensis as a crab seed by backcross and purification and rejuvenation. Breeding of the crab is returned nature by creating the original biological environment of crab survival, namely a natural crab pond, and carrying out a scientific and biological breeding method; and original biological environment and range suitable for crab growth are set, such as requirement on original biology of the crab pond, water quality, water temperature, breeding density, scientific bait dosage, water seed coverage rate and the like, and the unhealthy method which uses antibiotics, hormones and other medicaments and industrial synthetic feeds in a breeding process is eliminated, so that the bred crabs are big and strong, has rich cream, delicious meat and rich smell of wild crabs with average specification of between 150 and 250 grams. The crab can meet the requirements on export and pollution-free food, has high economic value and good social benefit.