Multi-Finger caliper tool is composed of electronics assembly, Multi-finger assembly,Caliper measuring assembly, Motor assembly.The primary function of Multi-Finger Caliper is to detect the deformation, bending, fracture, perforation and inside corrosion of tubing or casing with multi caliper fingers that are in close contact with the inner wall of the casing. Each caliper finger is connected to an independent non-contact displacement transducer that features small sizes, long service life, and high accuracy of measurement. The tool can connect to LANDAU Cased-hole Logging System or Warrior Logging System, made by Scientific Data Systems (SDS) Inc., to constitute a casing imaging logging system. All logging data, including multi-channels of borehole diameter, cartridge temperature, and cable head voltage are acquired by the tool and sent to the surface system via telemetry circuit and mono-cable. After data is processed by the computer software, the diagram of borehole inner diameter and a 3-D image of pipe are created to intuitively demonstrate the condition in detail of downhole tubing or casing.