An intelligent temperature compensating circuit is used to compensate the avalanche photodiode reverse bias voltage for offsetting the impact of environmental temperature on the avalanche photodiode, thus reducing the temperature drift of the system.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 devices, using temperature compensating circuit can effectively reduce system power consumption and cost.This circuit has better temperature compensation linear, and is more flexible for compensation coefficient setting than the circuit using thermistor.