A carbonation model of reinforced concrete structures subjected to mechanical load based on experimental work is proposed in the paper. Correspondingly, a series of reliability analysis and service life prediction is carried out and reasonable results are acquired. Besides the effect of concrete cover, it indicates that mechanical load impacts the reliability and service life of the reinforced concrete structures significantly through example calculation. In the case of concrete cover of 40mm, the service life is shortened nearly half under a tensile load of 60% while the service life is lengthened 30% under a compressive load of 30%. In service life design or long term performance assessment, more work should be done with the consideration of the mechanical load effect.