Aiming at the problem that the micro-fractures of the cement sheath destroy the integrity of the cement sheath, this work successfully prepared an oil-water dual-response self-healing material using sodium silicate as a self-healing agent, diatomite as a carrier, and ethyl cellulose as a surface coating material, and evaluated its self-healing effect. The results showed that the optimum calcination temperature of diatomite was 600℃. At this time, the specific surface area and pore volume of diatomite were the largest, and the pore distribution was uniform, which was most conducive to the adsorption of sodium silicate. Ethyl cellulose did not react with sodium silicate and diatomite. The 2wt% ethyl cellulose solution had the best coating effect on sodium silicate, and could form a smooth and dense film on the surface of diatomite adsorbed with sodium silicate. The optimum content of coated self-healing material in cement was 4wt%. After 14 days of self-healing, the micro-cracks of cement paste were completely closed, and the permeability of cement paste decreased to 0.31 mD, which was 69.31% lower than that of blank cement paste. After 14 days of self-healing, the compressive strength of cement paste with 4wt% coated self-healing material reached 26.6±1.3 MPa, and the recovery rate of compressive strength was 85.3%, which was 2.1 times that of blank cement paste. It was found by data fitting that the compressive strength recovery rate of cement paste increased first and then decreased with the increase of self-healing material content, and the self-healing effect was the best when the content was 4.5wt%. The results of XRD and TG analysis showed that when cracks occurred in the cement paste, the ethyl cellulose film on the surface of the self-healing material dissolved in oil, and then the self-healing agent sodium silicate consumed calcium hydroxide and water in the cement paste to form hydrated calcium silicate, and then filled the cracks to achieve self-healing.