The invention discloses a method of preparing a permeability-enhancing and strength-enhancing agricultural plastic mulching film by vehicle sound-absorbing cotton waste leftover materials. The raw materials comprise vehicle sound-absorbing cotton waste leftover materials, modified starch, calcium carbonate, plant fibers, glycidyl methacrylate, dicumyl peroxide and an auxiliary agent. By taking thevehicle sound-absorbing cotton waste leftover materials as a main raw material, the vehicle sound-absorbing cotton waste leftover materials are modified by starch and are mixed compatibly to be recovered, so that re-utilization of resource is achieved. Besides the characteristics of the mulching film in the prior art, the produced agricultural plastic mulching film also has the advantages of keeping temperature, preserving soil moisture, improving ground temperature, improving use ratio of light, preventing drops, improving light transmittance and insulating property, promoting growth of crops in seedling stage, can be degraded in a natural environment, meets the growth cycle of crops, becomes organic wastes if being degraded, can be also absorbed by soil, improves the plantablility and has good economic and social benefits.