Abstract: Described here in the paper are an endoscope device used for detecting the inner surface of the large-sized steel pipe and the design scheme thereof.Also analyzed are the structure,principle and technical characteristics of the said device.The facts as follows are revealed via the analysis.The device is capable of movement control and image and data transmission with network communication,and 360° full coverage detection of the inner surface via integrated multiple cameras so as to directly identify various surface defects on the inner surface of the steel pipe or the pressure pipeline,and moreover get the defect rapidly located and quantitatively analyzed.