The invention provides a multifunctional ecological inner wall coating material and a preparation method thereof, and belongs to the field of coating materials. The inner wall coating material is prepared by mixing the following raw materials: de-ionized water, an emulsion, a liquid aid, titanium dioxide, low-VOC (volatile organic compound) color paste, a functional composite material, white sand and a powder aid. The preparation method comprises the following steps: (1) adding the de-ionized water and the emulsion into a reaction kettle, adding the liquid aid and titanium dioxide in sequence while stirring, dispersing for 15 minutes, and performing color mixing by the low-VOC color paste according to the color sample design requirements of customers; (2) adding the functional composite material, the powder aid and the white sand into a powder mixer, mixing for 10 minutes, and discharging for later use; (3) slowly adding the discharged powder in the step (2) into the reaction kettle while stirring, uniformly mixing, checking, discharging and packaging. The coating material comprises functional materials such as a low-VOC emulsion, an environment-friendly aid, a lead-free pigment, a biological sterilization material, a humidifying material and a nanomaterial, and has the functions of decoration, protection, humidification, energy conservation, bacterial inhibition and killing, air purification, negative ion release and the like.