The invention relates to a method for synthesizing artificial soil from sediment. The soil comprises sediment, wormcast, a straw carbon source regulator, a pH regulator, a buffering agent and a microelement chelate, wherein the weight percentage of the sediment is 85%-95%, the weight percentage of the wormcast is 5%-15%, and 0.01-2,000 g of the straw carbon source regulator, 0.01-1,000 g of the pH regulator, 0.01-1,000 g of the buffering agent and 0.01-500 g of the microelement chelate are added to one ton of a mixture of the two substances. The method overcomes the defect of poorer stability of substrate products. The artificial soil produced from the sediment can effectively overcome bottlenecks of unstable substrate property, low plant safety and high environmental pollution risk, through raw material proportioning and fermentation, the application effect of the artificial soil is always kept excellent, and the artificial soil has the volume weight similar to that of mature soil, and can better fix root systems of plants, increase water-retention and air permeability and well coordinate environmental factors such as water, fertilizer, air, heat and the like required in the plant growth process.