The invention discloses a method for returning straws to a field. According to the method, straws are collected, naturally dried and crushed; the crushed straw is soaked in a treatment solution; filtering is carried out, and the soaking solution is removed; the straw is steamed; the steamed straw is buried in field ditches; an organic fertilizer is applied, and soil is used for covering and is compacted. According to the invention, the straw is crushed, soaked in the treatment solution and is steamed; a composite synergist (o-nitro phenol sodium, polyaspartic acid, potentilla anserine, gibberellin, hydroxyacetamide, and sodium tripolyphosphate) is added to the organic fertilizer; with microbes in the soil, lignin in the straw can be fully degraded, and straw decomposition efficiency is greatly improved. Therefore, straw returning time is shortened, and the occurrence of wheat root diseases under a corn straw returning condition is reduced.