This paper presents an adaptive tracking control method for a welding mobile manipulator with a kinematic model in which several unknown dimensional parameters exist. The mobile manipulator consists of the manipulator mounts on a mobile-platform. Based on the Lyapunov function, controllers are designed to guarantee stability of the whole system when the end-effector of the manipulator performs a welding task The update laws are also designed to estimate the unknown dimensional parameters. The simulation and experimental results are presented to show the effectiveness of the proposed controllers.