Measuring device and method for measuring relative motion amount of two ships during on-side supply

The invention discloses a measuring device and method for measuring the relative motion amount of two ships during side-close supply, wherein the measuring device comprises a supply ship and a ship to be supplied, a crane is mounted on the supply ship, a supply object is hung on the crane; the measuring device also comprises a measuring unit comprising a shell, and a computer and a plurality of measuring parts are mounted in the shell; a wireless transmitting device is arranged outside the shell; and the wireless transmitting device and the plurality of measuring parts are connected with the computer. Through the measuring device, the descending speed and acceleration of the supply object and the height relative to the measuring device can be obtained in real time, and an operator can conveniently regulate and control the posture of the supply object so as to guarantee the quality of the supply object; and the measuring device can automatically switch all parts at different stages, the accuracy and reliabilit