Wood is a biomass material that is easily eroded by wood-rotting fungi. Coptis chinensis is a natural green plant, which has an inhibitory effect on most microorganisms. Based on the highly toxic effects of the currently used wood chemical preservatives on humans, animals, and the environment, Coptis chinensis was selected to perform decay resistance experiments of wood in this paper. The active ingredients with bacteriostatic properties in Coptis chinensis were separated and screened via chemical treatment, and their structure was identified via nuclear magnetic resonance spectroscopy. The primary bacteriostatic components in Coptis chinensis were berberine hydrochloride, palmatine, and jatrorrhizine. The bacteriostatic zone experiment with a single component and different compounds for white-rot and brown-rot fungus were tested by the disc agar diffusion method. The bacteriostatic effect of berberine hydrochloride in a single active fraction was better. The three-fraction compound had the best bacteriostatic effect and was equivalent to alkaline copper quaternary. The natural active bacteriostatic fractions in Coptis chinensis had noticeable inhibitory effects on white-rot fungus (Trametes versicolor (L.) Lloyd) and brown-rot fungus (Gloeophyllum trabeum (Pers.) Murrill). The minimum bacteriostatic concentration was 0.01 g/mL. The results showed that Coptis extracts had potential as a wood protectant.