The invention relates to a preparation method of a nano silver material for repair of damage of a spinal cord and peripheral nerves, which belongs to the field of repair of damage of human or animal spinal cords and peripheral nerves with a tissue engineering method. The repairing material is prepared by mixing collagens (I, III and IV type), chitosan and nano silver. The speed for lowering a silicone tube filled with mixture of the nano silver, the collagens and the chitosan into cold leaching solution and/or the temperature of the cold leaching solution are/is changed so that the internal structure of the material for repairing the tissue engineering of the spinal cords and the peripheral nerves can be provided with an axial micro tube matrix, and the inner surfaces of micro tubes are provided with positive charges uniformly distributed. The nerve repairing material for tissue engineering can substitute the material for grafting of autologous free nerves, avoid the iatrogenic damage to the supply area, speed up the growth of the regenerated axon of the peripheral nerve, and shorten the nerve repairing time. Therefore, the invention can be widely applied in the surgical repair of clinical spinal cord injury and long-term peripheral nerve defects.