The invention discloses a composite soil conditioner which belongs to the technical field of fertilizers, and mainly includes the following raw materials in parts by weight: 100-500 parts of humic acid with 45% of organic matter, 0.5-2 parts of ferrous sulfate, 8-100 parts of polyglutamic acid, 15-150 parts of polyaspartic acid, 1-50 parts of earthworm powder, 12-180 parts of shell powder, 10-50 parts of soybean cakes, 1-10 parts of amino-oligosaccharin, 10-30 parts of attapulgite powder and 10-20 parts of microorganism composite zymophyte. The composite soil conditioner provided by the invention can provide nutrition, adjust and balance the pH value of soil, adjust the soil microflora, improves the water retention, fertilizer maintenance and breathability of soil, degrade organic pollutants, releases phosphorus and potassium, has the antagonism function to heavy metals or can be used for precipitating heavy metals, reduces absorption of crops to heavy metals, and has the multiple conditioning functions of detoxifying the soil, building up fertility, improving the physical properties and micro-ecological environment of soil.