Abstract: Casing will be damaged by corrosion with the corrosive oil and gas fluid during the process of oil and gas production.The stress caused by high pressure production fluid will affect the rate of casing corrosion. This paper focuses on the phenomenon thatthe external stress which loads on the corrosive casing will accelerate corrosion rate and shorten the casing service life significantly.Combining the theory of mechanochemical effect, the analytical model is established for casing corrosion accelerating rate by externalstress with two dimensions stress and three dimensions stress, and the analytical formula for calculating the stress effect on casing servicelife is put forward. According to the sample result, the result obtained from the model is consistent with the literature result achieved byexperimental research. It is concluded that the higher the stress on casing, the faster the actual casing service life gets shorter. The modeland the calculating result can work as reference for exact determination of casing servicing life.