To improve the on-line monitoring ability for lithium battery temperature, a distributed Raman fiber temperature measurement system was set up by dual-channel demodulation scheme, which adopted an external trigger mode to realize the coordinated working state. Results show that the temperature accuracy of each direction reaches ±1 ℃ within the distance of 10 m at normal temperature. After 8 tests, the temperature errors are all within 0.17 ℃, indicating that the system can maintain good stability at room temperature and meet the design conditions. The system can meet the requirements of temperature measurement for lithium battery, accurately feedback the abnormal local temperature, and effectively prevent various accidents cause by lithium battery. Within 10 m sensing distance, the maximum error is only 2 m, which meets the temperature measurement requirements of lithium batteries. Simulation test results show that the system can identify and locate faults accurately, which proves that the system has excellent distributed testing performance. The DTS system can achieve a resolution of ±1 m that can quickly respond to the temperature change caused by lithium battery failure.