The invention discloses a method for preparing a light general plastic composite material by adding bulk industrial solid wastes, and belongs to the field of preparation of chemical materials. The method comprise the following steps: with the bulk industrial solid wastes and general plastic as main raw materials, performing surface modification on the bulk industrial solid wastes to improve compatibility with the general plastic, improving the mobility and processing performance of the composite material by using a compound plasticizer, and under the combined action of an appropriate amount of a foaming agent and auxiliary agent, mixing, granulating and forming to prepare the light general plastic composite material added with the bulk industrial solid wastes. The method is simple and convenient in process and low in cost; the light general plastic composite material is light in weight, high in strength and high in added value; the light general plastic composite material prepared by the method has the characteristics of high filling amount of the industrial solid wastes, low density, good mechanical properties, strong impact resistance and the like, has excellent buffering and damping, sound-insulating and heat-insulating, insulating, corrosion-resistant and mold-resistant performances and the like; light environmentally friendly building materials and engineering products made of the light general plastic composite material can be widely applied to construction, chemical industry, metallurgy, transportation and other fields.