In recent years, with the continuous increase of foreign crude oil imports and the decline of domestic oilfield production, different oil products may need to be transported together by the same oil pipeline during the transportation process.The fourth oil pipeline of Qingtie is taken as an example. Combined with the actual parameters, the pipe wall is discretized by using the finite element analysis method of ANSYS and the hexahedral structural grid. The thermal structure coupling problem of the buried pipeline is solved, and the corresponding thermal stresses of the straight pipe section and the bent pipe section at different temperatures are calculated respectively. Based on the theory of fracture mechanics,the number of annual limit cycles under different service life is calculated, and the influence of temperature alternation on pipeline fatigue life is analyzed, which provides a theoretical basis for the safe transportation of cold and hot crude oil pipelines.