Abstract: In this paper, the best estimation in-pile corrosion model of N36 zirconium alloy cladding was established based on the Arrhenius equation by using the poolside examination data. Due to the lack of corrosion data before corrosion transition, N36 zirconium alloy cladding corrosion model before corrosion transition was only a function of time, while the corrosion model after corrosion transition was a function of cladding temperature and time. N36 zirconium alloy cladding corrosion model was established by adding engineering factors to the best estimation corrosion model. N36 zirconium alloy cladding corrosion bound model was established based on minimum corrosion transition point. The results show that the N36 zirconium alloy cladding corrosion model agrees well with the verification data and can be used for the simulation of N36 zirconium alloy cladding corrosion behavior in reactor.