A method for preparing a composite coated separator of thermal resistance and high air permeability, comprising: preparing an MOF coating slurry: separately dissolving 0.8-1.0 g of copper(ii) nitrate trihydrate and 0.4-0.6 g of trimesic acid in 150-170 mL of ethanol, mixing the two after complete dissolution, stirring at room temperature for 30-120 min or sonicating for 20-50 min to obtain a precursor dispersion, and washing the resulting dispersion with ethanol and then drying in a vacuum drying oven at about 160 °C for 12 h to obtain an MOF product; and finally, adding the MOF product and PVDF into NMP in a certain mass ratio, and stirring and dispersing for 60 min to obtain the MOF coating slurry; preparing a hydrotalcite coating slurry: uniformly mixing 50-70 parts of ultrapure water and 0.3-0.6 parts of a dispersant as per part by weight, then adding 20-40 parts of magnesium aluminum hydrotalcite powder, and after stirring at a high speed, adding 4-8 parts of a thickening agent and uniformly mixing; and grinding the resulting slurry by a sand mill, adding 2-5 parts of a binder and 0.05-0.15 parts of a wetting agent, and stirring uniformly to obtain the hydrotalcite coating slurry; preparing a composite coated separator of thermal resistance and high air permeability: applying the hydrotalcite coating slurry prepared in step on two sides of a base membrane through roller coating, and drying the base membrane to obtain a semi-finished hydrotalcite coated membrane; and using the semi-finished hydrotalcite coated membrane as a base membrane, applying the MOF coating slurry obtained in step on two sides of the membrane through mixed coating, and drying the membrane to obtain the composite coated separator of thermal resistance and high air permeability. preparing an MOF coating slurry: separately dissolving 0.8-1.0 g of copper(ii) nitrate trihydrate and 0.4-0.6 g of trimesic acid in 150-170 mL of ethanol, mixing the two after complete dissolution, stirring at room temperature for 30-120 min or sonicating for 20-50 min to obtain a precursor dispersion, and washing the resulting dispersion with ethanol and then drying in a vacuum drying oven at about 160 °C for 12 h to obtain an MOF product; and finally, adding the MOF product and PVDF into NMP in a certain mass ratio, and stirring and dispersing for 60 min to obtain the MOF coating slurry; preparing a hydrotalcite coating slurry: uniformly mixing 50-70 parts of ultrapure water and 0.3-0.6 parts of a dispersant as per part by weight, then adding 20-40 parts of magnesium aluminum hydrotalcite powder, and after stirring at a high speed, adding 4-8 parts of a thickening agent and uniformly mixing; and grinding the resulting slurry by a sand mill, adding 2-5 parts of a binder and 0.05-0.15 parts of a wetting agent, and stirring uniformly to obtain the hydrotalcite coating slurry; preparing a composite coated separator of thermal resistance and high air permeability: applying the hydrotalcite coating slurry prepared in step on two sides of a base membrane through roller coating, and drying the base membrane to obtain a semi-finished hydrotalcite coated membrane; and using the semi-finished hydrotalcite coated membrane as a base membrane, applying the MOF coating slurry obtained in step on two sides of the membrane through mixed coating, and drying the membrane to obtain the composite coated separator of thermal resistance and high air permeability.