A Bacillus thuringiensis absorbent is composed of the carrier (soil-mineral micron-particles) and insecticidal protein in mass ratio of (1-5): (1-50). Its preparing process includes such steps as extracting and purifying insecticidal protein, preparing its solution, preparing soil-mineral micron-particles, preparing its suspension, and adsorbing the insecticidal protein. Its advantages are high insecticidal activity, firm adsorption, high resistance to ultraviolet degradation, and high degradation speed in soil.