The pipeline robot would detect the corrosion defects effectively which presented in the oil and gas pipeline, but the existed crack defects in the pipeline would not be effectively detected. A fluiddriven pipeline crack detect robots probe structure was designed, which would be used to detect pipeline axial crack defects. The general probe structure, the spring supporting structure, the wheel structure and the probe structure were designed. The structure of the probe was tested, the results show that the structure of the probe running distance exceeded 250 km. The designed probe lay a foundation for the development of crack detection robot.