The invention provides a biological cultivation method of a sea horse, which comprises the following steps of: establishing a cultured biological system, cultivating a newborn sea horse, cultivating a young sea horse and cultivating an adult sea horse. In the sea horse cultivating technology provided by the invention, the supply of bait under an industrial condition is ensured by establishing thecultured biological system, accelerating maturity and cultivating the bait; diseases are effectively prevented and treated and the surviving rate is increased; the mature rate and the seedling yield can be greatly increased; the surviving rate of sea horse seedlings is 62.38%; the nurturance surviving rate is 89.52%; the seedling yield per fetus is 405.2; the unit yield is 0.613kg/stere; and the biological cultivation method is a new technology capable of realizing industrial cultivation.