Abstract: As for gas pipeline, the thermal expansion and contraction deformation always lead to the thermal stress, which poses a threat to the pipeline. In the article, the finite element simulation method is used to calculate the thermal stress generated in the pipeline. Then the factors influencing the thermal stress in the pipeline are analyzed. The results show that the thermal stress of the pipeline is distributed in the direction of the pipe ring when the internal pressure and the external pressure are neglected. With the distribution of the temperature inside and outside the pipe, the maximum principal stress always appears on the wall with relatively small temperature. At 20 ℃, when the pipe wall thickness increases, the corresponding pipe thermal stress is reduced. On the other hand, the thermal stress decreases first and then increases. Lastly, the maximum concentration of thermal stress tends to occur at fixed constraints. The thermal stress of the pipe with fixed constraint on one end is more intense with the temperature. The thermal stress of pipe with fixed constraint on two ends and pipe with not constraints changes relatively flatly.