On the basis of introducing the nutrient composition and biogas fertilizer, the influence of biogas fertilizer on soil, crops and environment are summarized. Biogas fertilizer can improve soil structure, increase soil organic matter, available nutrient contents and enzyme activity, increase crop yield, quality and resistance, and relieve the non-point source pollution effectively. The harmlessness, application technology and risk are analyzed. Some suggestions are put forward to control the source pollution, strengthen the research of fermentation technology, define the standard of biogas fertilizer, and carry out large and medium-sized biogas engineering.