NOVELTY - Preparing biogas by traditional Chinese medicine residual, involves wetting: crushing the traditional Chinese medicine dried or wet residual, then adding water, wetting; inoculating and regulating carbon nitrogen ratio by bacteria agent: adding microbial fermented inoculums to the wetted medicinal residual, and adding urea or mud,; pre-fermenting; then adding fermented and pre-fermented traditional Chinese medicine residual to stirring tank (1), and adding biogas slurry and water, stirring uniformly, loading fermentation raw material to fermentation tank (2).    USE - For preparing biogas by traditional Chinese medicine residual (claimed).    ADVANTAGE - The method uses effectively the traditional Chinese medicine residual, which makes waste profitable and overcomes the difficulties that traditional Chinese medicine residual is difficult to dispose, stacked nowhere, and exists environmental pollution in the past; and has pre-fermented traditional Chinese medicine residual.    DETAILED DESCRIPTION - Preparing biogas by traditional Chinese medicine residual, involves (a) wetting: crushing the traditional Chinese medicine dried or wet residual, then adding water, wetting; (b) inoculating and regulating the carbon nitrogen ratio by bacteria agent: adding microbial fermented inoculums to the wetted medicinal residual, and adding urea or mud, or the mixture of urea and mud as nitrogen source to it so as to regulating the carbon nitrogen ratio (mass ratio) of the fermented material to 5-200:1, preferably 10-50: 1, further preferably 25-40:1, and furthest preferably 30:1; (C) pre-fermenting: after collecting and piling up the drug residual, fermenting under oxygen-shielding condition, obtaining the fermented and pre-fermented traditional Chinese medicine residual; (D) adding biogas slurry to perform acid fermentation: adding the fermented and pre-fermented traditional Chinese medicine residual to a stirring tank (1), and adding biogas slurry and water, stirring uniformly, loading the fermentation raw material to a fermentation tank (2), producing coarse biogas under sealing condition, drawing forth the biogas from the fermentation tank or by a non-continuous mode. An INDEPENDENT CLAIM is included for device for preparing biogas by traditional Chinese medicine residual, comprising a stirring tank used for stirring the traditional Chinese medicine residual, a biogas fermentation tank connected by a feeding pump and pipeline and stirring tank, a filtering device connected by the pipeline, pump, and the bottom of the biogas fermentation tank, and used for solid liquid separating the fermented waste liquid, a gas-liquid separator connected by the pipeline, the top of the biogas fermentation tank, and used for initially purifying the produced biogas, a desulfurizing tower connected by the pipeline and the top of the gas-liquid separator, and a biogas storage tank connected by the pipeline and the top of the desulfurizing tower.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of For preparing biogas.    Stirring tank (1)    Fermentation tank (2)    Marsh gas fermentation tank (3)    Slurry pump (4)    Solid-liquid separation (5)    Gas-liquid separating tank (6)    Desulphurization tower (7)    Marsh gas storage tank (8)