NOVELTY - Biological sludge leaching involves preparing inoculum of strains for biological sludge, where strain comprises Thiobacillus thiooxidans TS6, Thiobacillus ferrooxidans LX5, Pichia spartinae D13, Galactomyces sp. Z3 and Rhodotorula mucilaginosa R30, and the preservation number of Thiobacillus thiooxidans TS6, Thiobacillus ferrooxidans LX5, Pichia spartinae D13, Galactomyces sp. Z3 and Rhodotorula mucilaginosa R30 is CGMCC NO.0759, CGMCC NO.0727, CGMCC NO.3035, CGMCC NO.4298 and CGMCC NO.1147, respectively.    USE - Method for leaching biological sludge (claimed).    ADVANTAGE - The method is cost-effective, and enables to produce the product with improved nutrient value and convenient for subsequent recycling.    DETAILED DESCRIPTION - Biological sludge leaching involves preparing inoculum of strains for biological sludge, where strain comprises Thiobacillus thiooxidans TS6, Thiobacillus ferrooxidans LX5, Pichia spartinae D13, Galactomyces sp. Z3 and Rhodotorula mucilaginosa R30, and the preservation number of Thiobacillus thiooxidans TS6, Thiobacillus ferrooxidans LX5, Pichia spartinae D13, Galactomyces sp. Z3 and Rhodotorula mucilaginosa R30 is CGMCC NO.0759, CGMCC NO.0727, CGMCC NO.3035, CGMCC NO.4298 and CGMCC NO.1147, respectively. The selected strains are inoculated into each culture medium and, then placed in a shaker at 25-28 degrees C twice, where the rotating speed is 180-200 rotations per minute, where the Thiobacillus thiooxidans TS6, Thiobacillus ferrooxidans LX5, Pichia spartinae D13, Rhodotorula mucilaginosa R30 and Galactomyces sp. Z3 in the volume ratio of 3-5:3-5:0.5-1:0.5-1:1, respectively. The medium for Thiobacillus thiooxidans TS6 comprises (grams per liter): ammonium sulfate (0.4), monopotassium phosphate (3.0), magnesium sulfate heptahydrate (0.5), calcium chloride dihydrate (0.25) and sulfur powder (10). The medium for Thiobacillus ferrooxidans LX5 comprises (grams per liter): ammonium sulfate (3.5), potassium chloride (0.119), dipotassium phosphate (0.58), calcium nitrate tetrahydrate (0.168), magnesium sulfate heptahydrate (0.583), iron(II) sulfate heptahydrate (4.42)and 10N sulfuric acid (2.5), the pH is adjusted with 10 N sulfuric acid. The medium for Pichia spartinae D13, Galactomyces sp. Z3 and Rhodotorula mucilaginosa R30 comprises (grams per liter): potato (200), sucrose or glucose (20), and the pH is adjusted with 10 N sulfuric acid (2.5). The strains are immersed in a reactor containing biological sludge, and then cultured for 1.5-2 days under aerobic condition at 8-35 degrees C. The obtained material is filtered in a filter press with diaphragm chamber, where modified sludge feed time is 1-3 hours, high-pressure water squeeze packing time is 1-2 hours, feed pressure is 0.6-0.8 megapascal and diaphragm squeeze pressure is 1.2 ~ 1.6 megapascal.