The embodiment of the invention discloses a temperature measurement device and method of a large-core-diameter multi-mode optical fiber. The device is characterized by comprising a sweep frequency light source, a first optical fiber coupler, an auxiliary interference module, a main interference module, a data collection module and a data processing module, wherein the sweep frequency light sourceis used for providing linear sweep frequency light with central wavelength being 1550nm for the device; the first optical fiber coupler is used for dividing the linear sweep frequency light into a first sweep frequency light signal and a second sweep frequency light signal; the auxiliary interference module receives the first sweep frequency light signal to generate a clock signal; the main interference module receives the second sweep frequency light signal to generate a beat frequency interference signal; the data collection module receives the clock signal and the beat frequency interference signal and outputs the signals to the data processing module; and the data processing module generates temperature data of the large-core-diameter multi-mode optical fiber based on the signals received by the data collection module. Therefore, measurement of the temperature of the large-core-diameter multi-mode optical fiber is realized simply and rapidly, measurement efficiency is greatly improved, and measurement cost is lowered.