The invention provides internal wall paint with functions of mould proofing, moisture prevention and heat-insulating performance, and a preparation method thereof, belonging to the building material field. The paint in every 100 weight portion comprises 1 to 40 weight portions of a moisture absorbing material, 2 to 20 weight portions of a heat insulating material and 0.1 to 5 weight portions of a mould proofing material. The internal wall paint takes porous materials such as portiforium expanded perlite, attapulgite, sepiolite, diatomite, zeolite, etc. as a material with the humidity adjusting function, takes materials with low heat conductivity coefficient such as hollow glass bead, hollow ceramic bead, closed pore expanded perlite and silicon dioxide aerocolloid as a heat insulating material, and takes metal oxide, a nanometer material and zinc pyrithione as organic and inorganic composite mildew proofing materials. The paint has the moisture absorbing quantity more than 180g/m<2>, the moisture releasing quantity more than 140g/m<2>, the mould proofing capability in zero grade, the mold resistance more than 98 percent, and the coefficient of heat conductivity not more than 0.040W/m.K, can be applied to the building surface, and has the functions of mould proofing , moisture prevention and insulating heat besides the function of the internal wall decorative material.