Hydrogenated acrylic rosin (HAR)/polyacrylate composite emulsions were prepared by seeded semibatch emulsion polymerization method. The effect of HAR amount on monomer conversion rate, coagulum rate, and gel fraction of the composite emulsions as well as the water absorption ratio, adhesion properties, and thermal durability of the HAR/polyacrylate composite latex films was studied; the composites were also characterized by Fourier transform infrared spectroscopy (FT-IR), gel permeation chromatograph (GPC), differential scanning calorimetry, and thermogravimetry. The results showed that with the increase of HAR amount, the monomer conversion rate, gel fraction, molecular weight, and water absorption ratio were all decreased, and the coagulum rate and molecular weight distribution increased. HAR had good compatibility with polyacrylate, and when HAR amount was 4 wt%, the HAR/polyacrylate composite latex film had superior adhesion properties and thermal durability.