The invention relates to a distributed optical fiber temperature measurement method and system. The method comprises steps: two temperature measurement channels are adopted, and signal light is injected to a sensing optical fiber alternately from both ends of the sensing fiber; one temperature measurement channel acquires, at one end of the sensing optical fiber, backscattered light of the signallight injected from the end, and the other temperature measurement channel performs the same operation at the other end of the sensing optical fiber; and the acquired backscattered light is processedto obtain a temperature demodulation formula, and the temperature value of each point on the sensing optical fiber can thus be solved. The method in the invention adopts two temperature measurement channels for measurement, the process of solving temperature attenuation coefficients of two optical paths is avoided, the complexity of the temperature demodulation formula is thus reduced, and measurement errors can be reduced.