Optical whispering-gallery mode microsensors have been proven to measure temperature with high accuracy and sensitivity. In this work, we put a silica microsphere which is coupled to a fiber taper on a superconductive tape to characterize the electrical conductivity variation against temperature. The superconductive tape was placed inside a chilling chamber. Liquid nitrogen is used to make the air temperature in the lab-made chamber lower than the critical temperature (~ 110 K) of the high-temperature superconductor. A distributed feedback laser at 1516 nm is used to excite the resonance in the microsphere. The optical signal, particularly the resonance wavelength shifts, is recorded by a Picoscope corresponding to temperature increment. Meanwhile, a T-type thermal couple is used to calibrate the temperature data of the superconductive tape to obtain the relationship between temperature and resonance wavelength shifts. The electrical resistivity of the superconductor is measured by the 4-point probe method. The sensitivity of the optical sensor is determined by the thermal expansion and thermo-optic coefficients of the silica material. The measured sensitivities vary from 3.6 pm/K to 5.5 pm/K. The quality factor of the resonator under low temperature reaches 2.2 × 106. The present study has demonstrated the potential of WGM microsensors for determining the critical temperature and monitoring the temperature variation of superconductors.