The invention discloses a metro tunnel fracture surface deformation detection system, belonging to the tunnel engineering monitoring technical field. The system comprises a fracture surface scanning device, a mileage positioning device, an electrical equipment control device, a power source, a track detection vehicle and a station data processing system, wherein, the fracture surface scanning device, the mileage positioning device and the electrical equipment control device are arranged on the track detection vehicle; the power source is respectively connected with the fracture surface scanning device, the mileage positioning device and the electrical equipment control device through a power source convertor to supply power for the fracture surface scanning device, the mileage positioning device and the electrical equipment control device; a PLC controller is arranged in the electrical equipment control device; a rotary coder in the mileage positioning device, a sensor in the fracture surface scanning device and a rotary table stepped driver are respectively connected with the PLC controller; the PLC controller is connected with a wireless communicator through a wireless communicator in the station data processing system. The whole detection system of the invention has high portable integration degree, automatic operation process, convenient operation, low specialty technical requirements, rapid operation speed, extremely-time section surface measuring and high measuring precision, and the system precision is less than 3mm.