This paper presents a temperature compensating circuit which is used in distributed optical fiber Raman temperature sensor. The temperature compensating circuit through temperature compensation for the avalanche photodiode reverse bias voltage to offset the impact of environmental temperature on the avalanche photodiode, thus reducing the temperature drift of the system. By using this technology, the system measurement error caused by ambient temperature drift can be controlled within ±0.1 ℃ from 0 to 60 ℃. Compared with traditional constant temperature device, using temperature compensating circuit can effectively reduce system power consumption and cost.