A novel robot measurement system with 4 degrees of freedom is presented for large size in-pipe surface inspection and inner diameter measurement. According to different sizes of objects, the structure of robot can be regulated automatically due to the unique design so that the effective measurement range can be φ 550~1 000 mm. The system is can quickly complete data acquisition of whole 3D surface in large pipeline, and on this basis, gives on-line the analysis report of surface quality characteristics and the high-accuracy measurement result of inner diameter at arbitrary position. In the design of the robot control system, an adaptive control strategy is proposed to suppress vibration disturbance induced from environment noise, the control scheme results in the measurement precision level of inner diameter being 0.002 mm. In addition, it is user-friendly to operate due to its intelligent and integrated software support with data acquisition, data processing, 3D reconstruction and surface quality evaluating functions. The difference value between the measurement result of the presented system and that of the high-precision inside micrometer is less than 0.005 mm.