The waterborne polyacrylate emulsions with different mass ratios of hard/soft monomer were synthesized by semi-continuous emulsion polymerization technology using methyl methacrylate (MMA), 2-ethylhexyl acrylate (2-EHA), methylacrylic acid (MAA) as hard monomer, soft monomer and functional monomer respectively, ammonium persulfate (APS) as initiator, Sodium dodecyl sulfate (SDS) and AEO-9 as emulsifier. Attenuated total reflection -Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, gel permeation chromatography, thermogravimetric analysis and dynamic thermomechanical analysis were utilized to characterize the bulk structures and properties of waterborne polyacrylate. The results show that the particle size of waterborne polyacrylate emulsions was approximately 100nm, the number average molecular weight and weight average molecular weight of lower molecular weight of polyacrylate copolymers was about 30000g/mol and 50000g/mol respectively. For polyacrylate film, the decomposition temperature increased slightly from 327.5℃ to 343.5℃ and the glass transition temperature decreased from 21℃ to -3.5℃. Moreover, the surface tension of polyacrylate emulsion decreased from 39.83mN/m to 36.71mN/m, the interfacial tension between emulsion and BOPP film decreased from 19.01mN/m to 4.87mN/m, the contact angle of emulsions on BOPP film decreased from 62.6° to 27.8° and the adhesion ratio increased from 50% to 95% with the decreases of mass ratios of hard/soft monomer, indicating that the improvement of the wettability of emulsions was conducive to obtain good adhesion. The wettability of emulsion is the best and the fastness is the highest when the mass ratio of hard/soft monomer is 7/13, which can satisfy the application requirement of polyacrylate emulsion on BOPP film.