Abstract: Organic-inorganic compound fertilizer of Biogas Residues is a new granular fertilizer with two-layer structure. This study, through field experiment, was to explore the appropriate amount of this new fertilizer on vegetables and the optimization techniques to further reduce leaching of nitrogen and phosphorus in vegetable fields. The results indicated that, the combined application of organic-inorganic compound fertilizer of Biogas Residues would significantly increase yields of head cabbage, leaf mustard and water spinach. Under the experimental conditions, the optimum amount of combined application of organic matter of biogas residue for head cabbage and leaf mustard was 600kg/hm₂, while for water spinach 450kg/ hm₂. When combined application of organic-inorganic compound fertilizer of Biogas Residues, appropriate amount and ratio of potash fertilizer would further improve the yield of head cabbage and water spinach, as well as significantly lower concentration of nitrate nitrogen and total phosphorus in soil column of water percolation. Best ratio of N:P₂O₅:K₂O for head cabbage and water spinach were 1:0.3:1.3 and 1:0.5:0.7 respectively. At leaf mustard and head cabbage rotation system, the recommended fertilizer mode of chemical fertilizer combined with biogas residues increased yields by 5.1% and 11.9% respectively compared with conventional fertilization, and increase net income by 3.9% and 11.5% respectively; total apparent digestibility of nitrogen and phosphorus for double-cropping vegetables had an average increase of 12.5% and 12.4%, while the concentration of nitrate nitrogen and total phosphorus in soil column of water percolation was only 53.3% and 84.6% compared to conventional fertilization. The results provide a scientific basis for application of the new organic-inorganic compound fertilizer of Biogas Residues.