The sludge from biogas production can be used as organic fertilizer which functions as plant growth stimulator and bio-fungicide. Biogas residue fertilizer is not only with high quality, but also a good soil conditioner. According to the determination, applying biogas organic fertilizer can increase soil 0.17-0.6% of organic matter content, enhance 0.003-0.005% of total nitrogen and improve 0.01-0.03% of total phosphorus.