The invention discloses a floury soil improving method. The method comprises following steps: weighing following raw materials in parts by weight: 80 to 100 parts of low liquid limit floury soil, 2.4to 5 parts of cement, 3.2 to 6 parts of lime, 2.4 to 5 parts of lignin, 0.3 to 0.5 part of penta-sodium diethylene triamine penta-carboxylate, 0.4 to 1 part of polyol, 0.56 to 1.2 parts of acrylic emulsion, 1.6 to 3 parts of fly ash, and 1.28 to 2.4 parts of silica fume; adding the cement, lime, and fly ash into a high speed mixing-stirring machine, stirring for 0.5 to 1 hour, sequentially spraying lignin, penta-sodium diethylene triamine penta-carboxylate, polyol, silica fume, and acrylic emulsion under stirring, after addition, mixing the obtained mixture with weighed low liquid limit flourysoil, adding water, and blending to obtain a roadbed filling material. The unconfined compressive strength and water stability of mixed soil are improved; the permeability, compressibility, and brittleness of the mixed soil are reduced, and the strength of the mixed soil is guaranteed.