Disclosed are a crane and a control method therefor. The crane comprises a body, a boom, a luffing mechanism, a tension sensor, and a controller. One end of the boom is rotatably connected with the body. The luffing mechanism is respectively connected to the body and the boom. The tension sensor is disposed on the luffing mechanism, and the tension sensor is used for detecting a tension value of the luffing mechanism to the boom. The controller is electrically connected to the tension sensor and the luffing mechanism, and the controller is configured to determine that the arm length of the boom exceeds an arm length threshold if the tension value is greater than a tension threshold.