The excellent welding joints are obtained when the high strength automobile special steels are welded by CO2 laser. In order to improve the measuring accuracy of the test, the small hole method of measuring residual stress is revised necessarily. The simulation results coincide with the modified test values after ANSYS software being used to calculate residual stress. The influence of line energy on residual stress is researched for laser welding high strength steel plates by the test method. The test results show that the longitudinal residual stress reaches a maximum at a distance of approximately 2.5 mm far away from the center of welding seam，and the farther away from the weld seam, the smaller the value of residual stress is, and the residual stress ultimately achieves stability. The residual stress distribution of the initial stage is close to that of the stable stage by adding the arc plate in front of the welded specimen, which eliminates unstable phenomenon of residual stress of the initial stage. The transverse residual stress increases gradually and the maximum value of the longitudinal residual stress decreases when the line energy increases.