The invention relates to a composite soil conditioner, comprising biogas residues, pyroligneous acid, mineral powder, soluble chitosan, diethylene triaminepentaacetic acid pentasodium, a surfactant, tobacco powder, trehalose, di-rhamnolipid, a flocculating component, a penetrating agent, enteromorpha powder, modified zeolite, boron-zinc-magnesium-containing fungicide, a nano additive, an accelerant, pentaerythritol triacrylate and ionic liquid, preferably also comprising 4-methyl phenyl valerate which is equal to the ionic liquid in weight. The novel composite soil conditioner has excellent soil improvement and recovery performance, the utilization rate of the fertilizer by the crop is greatly increased, and the composite soil conditioner can significantly increase the yield, simultaneously also can improve the permeability of the soil and avoids side effects of heavy metals such as cadmium; thus, the composite soil conditioner is beneficial to crop growth and has a wide industrial application prospect.