The invention discloses a living microbial immobilization microsphere and a preparation method and application thereof. The method comprises the steps of microbial immobilization of a carrier, bacterial liquid suspension colonization, microbial active particles, proliferation and reculture and the like. The microsphere is spherical, has pores in the microsphere, has the diameter of 3.0-4.0 mm andthe specific gravity of 1.10-1.20 g/cm<3>, is alkalescent, and has good sedimentation performance and mechanical strength. The microsphere not only can play the chemical adsorption effect of the carrier on cadmium, but also can improve the growth and propagation environment of active microbes, thereby improving the extracellular adsorption and intracellular accumulation effect of active bacteria on cadmium. The maximum adsorption-accumulation amount in the range below initial Cd2 + concentration 250 mg/L can reach 158.77 mg/g. The living microbial immobilization microsphere has the advantagesof adopting cheap and easily available raw materials and being strong in process operability, environmentally friendly, easy to recover remarkable in treatment effect and the like, and has wide application prospect in the biological treatment process of heavy metal polluted water bodies.