The invention discloses a tourmaline inner wall coating and a preparation method thereof. The coating is prepared from, by weight, 10.00-20.00 parts of 800-mesh superfine tourmaline powder, 1.00-3.00parts of titanium dioxide, 4.00-8.00 parts of lithopone, 1-6 parts of light calcium carbonate, 5.00-10.00 parts of bentonite, 0.22 part of a dispersing agent and 40-51 parts of an adhesive. Accordingly, tourmaline components contained in the coating formula can release negative ions, the concentration of indoor negative ions reaches 780-1,300 ions/cm<3>, the requirement of people on fresh air in aroom can be met, the negative ions have the effects of respiratory care, blood circulation promotion, human body ion balance adjusting, fungus infection inhibiting, human body immunity enhancement and respiration regulation, in the whole formula, no toxic volatile organic component exists, the coating is environmentally friendly, healthy and free of toxicity, and the healthy and safe living environment is guaranteed.