Abstract: Abstract: The extension investigation of fire accidents by fire rescue agencies has been comprehensively promoted nationwide, and there is an urgent need to conduct research on the accountability methods and quality supervision methods for circulation channels. This article is based on the fire of lithiumion battery electric bicycles, and systematically studies the methods and technical means of full chain investigation. Research has shown that the full chain investigation can promote the special rectification of lithium battery products in the region, improve fire risk prevention and control capabilities, make the rectification measures of industry regulatory authorities more targeted, and provide new technical means for extending the investigation.

Key words: fire investigation, extension investigation, whole chain investigation, lithium?ion battery fire, electric bicycles fire