Dent is one of the important factors affecting pipeline fatigue life, and it will greatly reduce the fatigue life of the pipeline in service. And the peak cycle stress on the dented pipeline is the key parameter to calculate pipeline fatigue life. For typical II type dent in the pipeline, the finite element models are established under different circumstances. A large number of the calculation results are sorted, inducted, drew. On this basis, the results are analysed by univariate and multivariate. Non-linear regression analysis was utilized to fit the results by matlab, some specific expressions of the relationship between the dented pipeline peak cycle stresses and the dent depth, diameter and thickness of pipeline, and the dent longitudinal length are obtained after much calculation and analog.