To find a method of microbial immobilization which was efficient, fast and applied to biomass carrier — mycelial pellet, bacteria JH-9 were immobilized onto mycelial pellet formed by Aspergillus Y3. And the characteristics and internal structure of two different immobilization methods were compared. The simultaneity culture immobilization method could immobilize more bacteria and with little time with same bacteria inoculation count. Moreover, the volume and quantity of combined mycelial pellets formed by simultaneity culture immobilization method were bigger than that by adsorption immobilization method, and its diameter、weight and relative density were smaller. To immobilize with the same method, the size and volume of combined mycelial pellets were in direct proportion to the inoculation count of engineering bacteria, whereas its weight and relative density were opposite. Bacteria were immobilized and grew on each mycelium of combined mycelial pellets formed by simultaneity culture immobilization method.