In this paper the influence of carbon nanotubes (CNTs) on anticorrosion properties was discussed. KMnO4 modified carbon nanotubes were added into Waterborne PolyUrethane, then galvanized steel sheets were dipped into this composites to get a thin film and dried at 120 °C for 60 seconds. SEM observation show the film thickness was 3 µm and CNTs were dispersed in the polymer matrix. XRD demonstrated that some KMnO4 decomposed into K2MnO4 and MnO2. Polarization curves demonstrated the film exhibited excellent anticorrosion when the amount of KMnO4 modified CNTs was 6%.