The invention discloses antibacterial watercolor and a preparation method thereof. The preparation method comprises the following steps: mixing rare-earth, cyclohexanol, 8-carboxylquinoline and cyclohexane, sufficiently stirring for 15-25 minutes, and adding sodium m-carboxy benzoate to obtain a micro-emulsion M; adding tetra-n-butyl titanate into the micro-emulsion M, sufficiently stirring, centrifuging for 3-5 times, alternately washing with an acetone-ethanol mixed liquid and deionized water, drying, and grinding powder to obtain antibacterial powder N; and mixing epoxy resin, sodium benzoate, aluminum silicate, packing and a colorant, heating in water bath, adding the prepared antibacterial powder N, and performing ultrasonic dispersion to obtain the antibacterial watercolor. According to the antibacterial watercolor, the problem that mould easily grows on the surface of the traditional watercolor in a humid environment can be solved.