Abstract: In the identification of hazardous waste, the identification of liquid substances is a common situation, and there are many problems in each identification step. According to the characteristics of liquid waste, combined with Identification Standards for Solid Wastes: General Rules (GB 34330-2017) and National List of Hazardous Waste, and based on years of experience in the identification of hazardous waste, the authors analyzed the common problems in the identification process, and interpreted the technical methods for identifying hazardous waste of liquid substances. Key technical requirements were studied and proposed for the key steps of solid waste identification, list identification, and hazardous characteristic identification in the identification of hazardous waste. In the identification of solid waste, the technical route of "excluded analysis-traceability analysis-detection analysis" was proposed; in the step of list identification, the source of hazardous characteristics was emphasized as the main focus of attention, with waste generation process description as the main judgment basis; in the process of hazardous characteristic identification, attention should be paid to assessing the possibility of acute toxicity exposure and distinguishing the differences in the leaching toxicity and toxic substance content identification of liquid waste during sample testing.