The work aims to study corrosion behaviors of sintered NdFeB in interprocess as well as rust inhibition and mechanism of phytic acid. Surface morphology, elements composition, phase composition and element bonding energy state were tested with SEM, EDS, XRD and XPS, respectively. NdFeB was subject to serious corrosion in intergranular Nd-rich phase and thereby principal phase grain fell off, which was harmful to the coating adhesion. Phytic acid can efficiently inhibit the interprocess corrosion by adsorption by adsorption of phytic acid on the surface of NdFeB. The change of bonding energy in Nd, P and O elements also shows the effects of adsorption including chemical adsorption.