The utility model provides a powder using the tourmaline carrying cobalt to restrain the sulfate reducing bacteria activity and the preparation method thereof, relating to a bacteriostatic agent and a preparation method thereof, which aims to resolve problems that the present natural antibacterial agent is hard to be promoted, and that the safety and heat tolerance of the organic antibacterial agent which is easy to decompose and has short service life are bad. The percentage by mass of the tourmaline is 60 to 99.99 percent and the percentage by mass of the cobalt chloride is 0.01 to 40 against the invention. The preparation method is that: first, the nanometer tourmaline or submicron tourmaline is put into and mixed with the deionized water; second, the nitrate solution is added in order to adjust the PH value to 4 to 8; third, the cobalt and dispersing agent are added and mixed; forth, the mixing solution is cleaned by the deionized water after decompression and separation; fifth, the powder which undergoes the separation and cleaning processes is dried; sixth, the dried power is ground and burned, and then is grinded again to become the inorganic bacteria-restrained powder. With the invention which uses the nanometer tourmaline or submicron tourmaline applying the surface modification, ion exchange and solid phase synthesis method, the invention not only increases the cobalt-carrying quantity, but also improves the sterilization effect of the bacteriostatic agent.