Purpose: This paper aims to study the influence of the addition of calcium nitrite on the passive films of rebar to reveal what causes calcium nitrite to further prolong the durability service life of the reinforced concrete structures. Design/methodology/approach: A comprehensive experimental study of the passive films, such as components, surface morphologies, electric structure and compactness, was carried out in a saturated calcium hydroxide solution which is normally used to simulate concrete pore solution by using X-ray photoelectron spectroscopy, atomic force microscopy, Mott-Schottky and potentiostatic polarization, respectively. Findings: The results showed that the passivation behavior of rebar has been changed dramatically by the addition of calcium nitrite. That is, the passive film formed in the solution with the addition of 10 g/L Ca(NO2)2 had less donor density (Nd), more positive plat potential, smoother surface and lower content of Fehydrox than that formed in the solution without Ca(NO2)2. Originality/value: The study focuses on the passive films and provides a more clear cognition of the durability service life extension of the reinforced concrete structures caused by the addition of calcium nitrite.