The invention discloses a solid composite biological preparation for in-situ repairing and treatment on black and odorous water body bottom mud and a preparation method of the solid composite biological preparation. The solid composite biological preparation is characterized by comprising the following materials in parts by weight: 15-30 parts of a biological composite enzyme, 15-30 parts of a composite microorganism bacterial liquid, 10-15 parts of a microorganism growth promoter, 1-5 parts of a protection agent and 20-40 parts of dry powder aids. By adopting the solid composite biological preparation disclosed by the invention, due to physical, chemical and biological functions of the components upon bottom mud, the bottom mud can be greatly reduced, and the problem of black and odorouswater bodies can be remarkably alleviated; meanwhile, in-situ biological repairing and degradation functions can be activated and intensified, the self cleaning capability of the bottom mud is improved, and the bottom mud can be further reduced. The solid composite biological preparation has the advantages of being wide in raw material source, high in treatment efficiency, good in adaptability, low in cost, low in production and operation cost, and the like.