The invention relates to a loss measurement and calibration method of an optical switch in a distributed optical fiber temperature measurement device, and the method comprises the steps: 1), collecting a Stokes optical signal and an anti-Stokes optical signal at a position which is l away from a temperature measurement starting position at set temperature, wherein l is greater than the distance between the position where the optical switch is located and the temperature measurement starting position; 2) according to a temperature demodulation formula and the Stokes optical signal and the anti-Stokes optical signal collected in the step 1), calculating the ratio of the actual Stokes optical signal to the anti-Stokes optical signal at the calibration temperature T0; 3) obtaining an optical switch loss coefficient according to the ratio initial value of the Stokes light curve to the anti-Stokes light curve at the calibration temperature T0 and the ratio calculated in the step 2). The calibration method comprises the following steps: acquiring an optical switch loss coefficient by using the measurement method, and correcting a calibration curve after an optical switch of the distributed optical fiber temperature measurement device by using the optical switch loss coefficient. According to the invention, the temperature measurement precision of each point along the temperature optical fiber is improved.