Under vehicle-mounted action, buried polyethylene gas pipelines containing defects are prone to stress concentration, which will accelerate the damage of pipelines and lead to accidents. In this paper, a three-dimensional nonlinear coupling model of vehicle-tube-soil is established, and the loading vehicle type is a dynamic vehicle. In addition to weight, internal pressure, and defect depth, the internal relationship between vehicle speed and pipeline mechanical response is also explored, and the ultimate road load under different vehicle speeds and internal pressures is evaluated. The results show that the stress of pipes with defects is greater than that of pipes without defects. The soil weight can inhibit the effect of internal pressure on the pipeline to some extent. The maximum Mises stress of the pipeline was positively proportional to the defect depth coefficient, vehicle-mounted and internal pressure, and inversely proportional to the vehicle speed. The degree of influence on stress concentration of pipes with defects is as follows: internal pressure > defect depth > vehicle speed > vehicle speed; The ultimate load of the non-defective pipeline is higher than that of the defective pipeline, and the internal pressure has the greatest influence on the ultimate load of the defective pipeline, followed by the defect depth and speed.