Objective To develop an acrylic-based waterborne coating system by using MWCNT as the additive and examine the effect of the carbon nanotube content on the mechanical property and corrosion resistance of the coating. Methods The MWCNTs were dispersed in the acrylic resin by high-speed ball-milling. And acrylic composite coatings containing 0, 0. 5, 1, 3wt% MWCNT were prepared. The mechanical property and corrosion resistance of the coatings were evaluated using mechanical tests such as adhesion, impact resistance, bending resistance, and electrochemical impedance spectroscopy (EIS). Results The addition of carbon nanotubes obviously increased the adhesion of the coating, and the adhesion increased with increasing MWCNT content in the acrylic composite coatings, and there was no loss in other mechanical properties such as impact resistance and bending resistance at different MWCNT contents. Electrochemical impedance tests on the modified and unmodified coatings revealed that the coating containing 1% carbon nanotubes had the best electrochemical property. After 36 h immersion in 3. 5 wt% NaCl, the total impedance magnitude ( | Z | ) at 0. 01 Hz of acrylic coating and 0. 5% , 1% , 3% composite coating was 2. 5×103 Ω·cm2 , 1. 1×106 Ω· cm2, 1. 4×108 Ω·cm2 and 7×102 Ω·cm2 , respectively. Conclusion Due to the nano effect of the carbon nanotubes, the performance of the coating could be improved by low content of carbon nanotubes, but there was an optimal content, if the content exceeded this value the performance would decrease.