The phytic acid passivation film were acquired on the brass surface by Chemical immersion technology, and studied the film formation mechanism. The corrosion resistance of the phytic acid passivation film were studied by nitric acid droplet test, Neutral salt spray test and polarization curves. the morphology and components were analised by SEM and XRD. The potential-time curve were tested in the process of passivation on the brass specimen to speculate the Film-forming mechanism of phytic acid passivating film. Compared with chromate conversion, The corrosion current density of the phytic acid passivation on the brass surface is smaller than that of the chromate conversion film, and the corrosion rate is smaller than the chromate conversion. SEM and XRD results show that the surface of the passivation film is smooth and compact, and the main components are phytate, Al2O3 and ZnO. The potential-time curve show that the brass sample potential rise rapidly from ?0.172 V to ?0.157 V in the 60 s in the process of passivation. Then the speed of the potential rise gradually slow, finally, potential changes in tiny after 150 s. The phytic acid passivation film on the brass surface has good corrosion resistance, the process of film formation of phytate passivation film included two processes: dissolution of brass surface and formation of phytic acid passivation film.