The invention provides a calibration device and a calibration method of a tension sensor. A lever mechanism is arranged between a tension senor to be calibrated and a fixed bench below the tension sensor. The lever mechanism comprises an upper pull rod, a lower pull rod, a connection rod, a balancing rod, an adjusting rod and a counterweight. The tension sensor is hanged, the balancing rod is hanged below the tension sensor through the upper pull rod, one end, close to the upper pull rod, of the balancing rod is connected with one end of the adjusting rod arranged below the balancing rod, the middle part of the adjusting rod is connected with the fixed bench through the lower pull rod, and the other end of the adjusting rod is provided with a leveling bolt arranged vertically; and the balancing rod utilizes a lever principle to amplify the force of the counterweight, and the tension sensor connected to the other end of the balancing rod is calibrated. The calibration device is stable and reliable, and by adjusting the position of the counterweight, the calibration of large-range internal loads can be carried out.