The invention discloses a boarding bridge height measuring device. A boarding bridge comprises a rotary table and a bridge body. The bridge comprises a connecting end and a hatchway connecting end. The connecting end and the rotary table are hinged at a hinging center, and the hatchway connecting end is connected with a hatchway. The height measuring device comprises a support connected to the rotary table, a height measuring assembly and a control module. The height measuring assembly comprises an adapting piece connected to the support, a pull cord and a pull cord switch. One end of the pull cord is connected to the rotary table, after the direction of the middle of the pull cord is changed through the adapting piece, the other end of the pull cord is connected to the bottom of the bridge body, the direction of the pull cord is changed at the adapting point, and the distance between the connecting point between the pull cord and the bridge body and the hinging center is equal to the distance between the adapting point and the hinging center. The boarding bridge height measuring device and method have the advantages that the distance from the hatchway connecting end to the ground can be accurately measured, performance is stable, and cost is low.