The invention relates to an ecological organic soil improving agent and a preparation method thereof. The ecological organic soil improving agent is prepared from the following ingredients in parts bymass: 30 to 40 parts of livestock and poultry manure, 20 to 30 parts of weathered coal, 20 to 30 parts of biomass charcoal, 10 to 20 parts of humic acid, 10 to 20 parts of bone meal and 10 to 20 parts of mushroom slag. The ecological organic soil improving agent has high organic matter contents and balanced nutrients, the soil is thoroughly decomposed, and the ecological organic soil improving agent has the advantages of safety, high efficiency and no pollution. The sufficient resource utilization of industrial and agricultural solid wastes is realized; waste materials are changed into valuable materials; the economic benefits are high; the popularization values are realized.