The tribocorrosion behavior as well as the corrosion-wear interaction of Monel 400 alloy in seawater were investigated under varied loads. An abnormal antagonistic effect of corrosion on wear was found, which was highly related to the peculiar corrosion products in the shape of nanospheres only generated under the tribocorrosion condition due to the selective corrosion of Ni-rich components. A boundary lubrication layer, consisting of the nanospheres squeezed and spread by friction stress, leaded to the reduction of friction coefficient. Moreover, the material loss rate was greatly alleviated because the friction-induced surface delamination and sub-surface crack propagation were prevented.