The invention belongs to the field of a building material, and discloses composite clay substituting the natural sand and premixed concrete adopting the composite clay as a raw material. The composite clay comprises the following raw materials by weight percent: 45 to 75 percent of clay, 3 to 10 percent of shell powder, 5 to 20 percent of coal ash, 5 to 20 percent of slag, 5 to 20 percent of rice hull ash, 0.5 to 2 percent of quick lime and 0.5 to 1.5 percent of sodium carbonate. All components are added into water to be premixed, stirred, ground and rolled, and the obtained mixture is dried, granulated, screened and graded at the temperature of 200 to 300 DEG C to obtain a raw material for stirring the concrete. The composite clay is composited with cement, stones, mineral powder, a water reducing agent and water according to a given ratio to obtain the premixed concrete with excellent slump and tensile strength. The composite clay is adopted to substitute the natural sand to be used as fine aggregates in the premixed concrete, so that the corrosion resistance and durability of the concrete can be improved; moreover, the resources such as rice shell and shells are adequately utilized, the waste is converted into treasure, the market popularization value is high, and the application prospect is wide.