In the coal-water slurry gasification system, a reduction in the temperature of the syngas pipeline can cause acid gases to condense, which may lead to corrosion of the pipeline's inner surface and potentially result in perforation leaks. To enable prompt detection and precise localization of any leakage or damage within the syngas pipeline, The techniques were explored for identifying and locating such issues through distributed temperature sensing(DTS). An algorithm based on an adaptive variance threshold was proposed for DTS detection and localization. Initially, hierarchical clustering was utilized to recognize detected signals, facilitating differentiation between normal operating conditions and those indicative of leaks or damages. Following this, identified leak signals undergo processing via variance analysis combined with adaptive threshold settings to accurately determine leak or damage locations. This approach shows improved accuracy in pinpointing leak or damage sites compared to fixed threshold methods as well as selective average threshold methods, enhancing positioning precision by 0.32 m and 0.17 m respectively. A temperature measurement experiment conducted at a coal gasification facility successfully confirmed accurate identification of leakage or damage points.