The invention relates to the technical field of ships and provides a tensioning force calibration mechanism, a mounting method, a pipe cable laying system and a ship aiming to solve the problems that in the prior art, calibration of pre-tensioning force of a tensioner adopts a testing hanging block, the time and labor are wasted, more resources are occupied, and high risks occur to the ships and workers. The tensioning force calibration mechanism comprises a calibration beam, cylindrical steel castings for connecting moon pool wave absorbing plates and first hanging devices; the cylindrical steel castings are arranged at the two ends of the calibrated beam; and the first hanging devices are arranged on the calibration beam. Pre-tensioning force of a tensioner is calibrated in a calibration beam mode, assisting of the testing hanging block is not needed, and the technical requirements of different pre-tensioning force can also be quickly fed back. In addition, the tensioning force calibration mechanism, the mounting method, the pipe cable laying system and the ship all have the beneficial effects of being convenient to carry, easy to mount, flexible in operation, safe, reliable, economical and efficient.