NOVELTY - An improved matrix is prepared by (A) pre-treating of green plant waste, (B) composting product of the green plant waste and (C) preparing of improved matrix. The step (A) comprises providing sludge from domestic sewage plant or poultry excrement, grinding green plant waste to obtain green plant waste having grain size of 1-3 cm; measuring water contents of ground green plant waste; and respectively measuring water contents of ground green plant waste. The step (C) comprises adding humic acid or calcium superphosphate and uniformly mixing to prepare improved matrix.    USE - Method for preparation of improved matrix (claimed) useful for improving urban soil property.    ADVANTAGE - The prepared matrix improves fertility and physical structure of the green soil and reduces soil volume weight. It also promotes recycling of waste.    DETAILED DESCRIPTION - An improved matrix is prepared by (A) pre-treating of green plant waste, (B) composting product of the green plant waste and (C) preparing of improved matrix. The step (A) comprises providing sludge from domestic sewage plant or poultry excrement, grinding green plant waste to obtain green plant waste having grain size of 1-3 cm; and respectively measuring water contents of ground green plant waste to obtain green plant waste having grain size of 1-3 cm; and respectively measuring water contents of ground green plant waste. The step (B) comprises composting product of green plant waste, obtaining ground green plant waste and sludge from domestic sewage plant or poultry excrement at mass ratio of 10-70:30-90, adding urea (0-1 mass%) and uniformly mixing and detecting; composting mixture in rain sheltered place when water content is 40-60%, where composting height is 0.45-1.2 m and composting volume is 2-10 m3; composting and curing mixture for 20-40 days; when temperature is not increased any longer, and water content is less than 38%, obtaining composting product; when composting temperature during composting and curing is at 55-60 degrees C, turning over mixture for one time; when temperature is at 60-55 degrees C, turning over mixture for one time every 3-5 days; when composting temperature is less than 55 degrees C, turning over mixture for one time every 7-12 days; and when composting temperature is more than 70 degrees C, turning over mixture timely. The step (C) comprises firstly measuring pH, exchangeable cations, density, ventilation performance, and total primary nutrient, contents of organic substance, nitrogen (N), phosphorus (P) and potassium (K) of composting product; adding humic acid (0-0.3 mass%) or calcium superphosphate (0-0.3); and uniformly mixing to prepare improved matrix. The impurities have grain size of less than 2 mm in improved matrix is less than 5 mass, where EC is equal to 0.5-3.5 mS/cm, water content is less than 35 mass. The organic substance is greater than or equal to 20 g/kg. The total primary nutrient (N+phosphorus oxide+potassium oxide) is greater than or equal to 2.5 mass%, where dry density is 0.1-0.8 mg/m3, wet density is less than 1.2 mg/m3 and ventilation property is greater than 15%.