NOVELTY - Organic fertilizer comprises raw materials comprising 5-6 pts. wt. municipal domestic sludge, 3-4 pts. wt. chicken manure, 2-3 pts. wt. straw, 1-1.5 pts. wt. plant ash, and 0.5-1 pts. wt. pig manure or cow dung, where the content of total organic substances in the raw material is greater than or equal to 45% and the sludge is municipal domestic sewage refers to sewage discharged from urban sewage treatment plants or large food factories after wastewater treatment, moisture content of the municipal domestic sludge is less than 60%.    USE - The organic fertilizer is useful for cultivating dragon fruit (claimed).    ADVANTAGE - The cultivated dragon fruit has high-quality. The organic fertilizer prepared by the method improves municipal domestic sludge utilization rate, is environmentally-friendly and cost-effective.    DETAILED DESCRIPTION - Organic fertilizer comprises raw materials comprising 5-6 pts. wt. municipal domestic sludge, 3-4 pts. wt. chicken manure, 2-3 pts. wt. straw, 1-1.5 pts. wt. plant ash, and 0.5-1 pts. wt. pig manure or cow dung, where the content of total organic substances in the raw material is greater than or equal to 45% and the sludge is municipal domestic sewage refers to sewage discharged from urban sewage treatment plants or large food factories after wastewater treatment, moisture content of the municipal domestic sludge is less than 60%, and water content of the pig manure or cow dung after airing is 50-60%. An INDEPENDENT CLAIM is included for method for preparing the organic fertilizer, which involves naturally drying the above-cited raw materials, adding high temperature aerobic bacteria, uniformly mixing and fermenting mixture at 55-65 degrees C for 2-3 days, then raising the temperature and fermenting for 4-7 days, where the water content is reduced to 40-45%, cooling fermented mixture, adding the fermented mixture into potassium sulfate, potassium dihydrogen phosphate and uniformly stirring mixture at high temperature and maintaining at 42-46 degrees C for one month, where the water content is reduced to 30-35%, where the ratio of potassium sulfate, potassium dihydrogen phosphate and fermented mixture is 1:0.5-1:1.2-1.5, compositing mixture, adding mushroom residue, performing secondary fermentation of mixture, and drying and mechanically crushing mixture, and packaging finished product.