The invention discloses aqueous color paste and a preparation method thereof. The color paste comprises the following components by weight: 20-45 parts of organic pigment, 5-12 parts of aqueous acrylic resin, 0.8-12 parts of nanometer zinc oxide, 0.2-1 part of an aqueous dispersant, 0.3-1 part of an aqueous defoaming agent, 0.1-1 part of a stabilizer and 45-78 parts of water, wherein the organic pigment has a particle size of 10 to 20 [mu]m, and the nanometer zinc oxide has a particle size of 20 to 60 nm. The preparation method comprises the following steps: 1) adding grinding glass beads andwater into a reactor and carrying out uniform mixing; 2) sequentially adding the aqueous dispersant, the aqueous defoaming agent and the aqueous acrylic resin into the reactor, and carrying out uniform mixing; and 3) adding the organic pigment and the nanometer zinc oxide into a system obtained in the step 2), carrying out uniform mixing, and then carrying out filtering to remove the grinding glass beads so as to obtain the aqueous color paste. The aqueous color paste provided by the invention has moderate viscosity, good dispersion stability, and high hiding rate and good gloss after film formation.