Abstract: Based on the research of the wheeled robot seam tracking accuracy in 4 degrees of freedom,a new characterization assessment of seam tracking accuracy method was proposed,and 5-parameter model under D-H coordinate system in seam bias was built up as well.By this model,the main error sources affecting the accuracy of seam tracking is theoretically analyzed.Through the simulation analysis of fixed-step and variable step method of seam tracking control,the correctness and validity to accuracy of analytical methods and modeling presented in this paper were verified,the main reason affecting seam tracking accuracy was seam tracking control algorithm and robot positioning accuracy.The accuracy analysis method have guiding significance for seam tracking control of robot error compensation and the improvement of seam tracking control method.