The invention discloses a soil improvement composition. The soil improvement composition comprises, by weight, 400-700 parts of straws, 800-1300 parts of chicken manure, 20-40 parts of lime sulphur, 100-200 parts of calcium superphosphate, 250-500 parts of oil cake, 5-10 parts of nitrogen fixing bacteria and 5-10 parts of bacillus subtilis. The soil improvement method comprises 1, weighing components of the soil improvement composition, and 2, before plantation, digging a pit with the depth of 1-1.2m in the field, orderly paving straws, soil, chicken manure, soil, lime sulphur, soil, calcium superphosphate, soil, oil cake, soil, chicken manure, soil, nitrogen fixing bacteria, bacillus subtilis and soil in the pit from bottom to top. The soil improvement composition comprises multiple types of components, comprehensively improves soil and does not influence the environment.