The invention discloses a device and a method for culturing active anaerobic microorganisms in self-heating liquid. The device comprises a plastic bottle, a bactericidal sheet, a bottle cap, a heating device and a heat preservation device, wherein the plastic bottle is filled with a culture medium, and is provided with a bottle neck; an opening in the upper end of the bottle neck is sealed by an opening sealing membrane; the bactericidal sheet is arranged on the opening sealing membrane; the bottle cap caps the opening of the plastic bottle; the edge of the lower end of the bottle cap is connected with the upper end of an opening sealing ring which sleeves the bottle neck; the lower end of the opening sealing ring is connected with an rubber ring which is arranged on the bottle neck; a hollow cylinder is arranged in the bottle cap; after the opening sealing ring is torn off and the bottle cap is screwed on the plastic bottle downwards, the opening sealing membrane can be punctured by the tail end of the hollow cylinder, and the bactericidal sheet falls into the culture medium; the heating device is a heating patch; and the heat preservation device is a heat preservation box in which the plastic bottle can be put. The self-heating device provided by the invention is easy and convenient to operate, is low in economic cost and can be used for culturing anaerobic microorganisms without the help of a sterile workbench, a constant-temperature incubator and a professional technician.