A series of 4-maleimidophenol modified anionic waterborne polyurethane—acrylate (MWPUA) emulsions were prepared by in-situ polymerization with isophorone diamine (IPDI), poly-caprolactone diol (PCL), 2,2-dimethylolpropionic acid (DMPA), trimethylol propane (TMP), 4-maleimidophenol (4-HPM), methyl methacrylate (MMA) and butyl acrylate (BA) as main raw materials. Structure and properties of polymer were characterized by FT-IR, TEM, XRD, TGA and tensile testing. The effects of the content of 4-HPM on the properties of MWPUA emulsion and its films were also studied. The results showed that latex particle is ball-like, and has a core-shell structure. When w(4-HPM)=3.0wt%, the average particle size was 97.8 nm with narrow particle size distribution. Compared with the pure waterborne polyurethane (WPU), the crystallinity and thermal stability of MWPUA latex film has improved. The maximum decomposition rate of film decreased 8.1%, the tensile strength was up to 24.9MPa, water contact angle reached 103.2? water absorption ratio was as low as 8.8%.