流行病学调查（简称流调）是疾病预防控制机构发现传染病疫情或者接到疫情报告后依法采取的首要措施，是新型冠状病毒肺炎疫情处置的关键，也是快速控制疫情的前提。本文将流调在疫情响应中的本质归结为应急处置，指出流调的根本目的是控制疫情，通过运用作者亲身经历的一些案例，围绕“将疫情控制在最小范围”、现场快速处置、形成与验证假设、撰写报告加以阐述，并提出流调所面临的一些挑战。本文突出强调了现场调查的作用，提出在现场不但要侦查，还要假设，更要快速处置，并应及时将现场经验与发现问题转化为疫情防控的策略措施。本文还重点强调了通过全面查摆调查证据，形成和完善“证据链”，进而服务于验证假设的思想。新型冠状病毒肺炎疫情百年不遇，总结宝贵的现场流调经验将有助于我国精准处置疫情、保持病例动态清零状态以及应对未来其他重大公共卫生事件。“,”Epidemiological survey is a primary measure, following an epidemic detection and report, implemented by agencies for disease control and prevention according to law. It is the key to disposing coronavirus disease 2019 (COVID-19) epidemic and the premise of rapidly controlling this epidemic. In this paper, the essence and fundamental purpose of epidemiological survey in epidemic response was respectively attributed to emergency disposal and epidemic control. Fresh COVID-19 cases experienced by the author were used to introduce “limiting an epidemic to the minimum scale”, on-site rapid disposal, developing and verifying a hypothesis, and report writing and suggest some challenges in the survey. This paper highlighted the role of on-site survey that should be not only investigating, but also hypothesizing and, in particular, rapidly disposing. The on-site experience and problems should be particularly transformed into strategies and measures for epidemic prevention and control in time. This paper also emphasized thinking of forming and perfecting the “evidence chain” by systematically checking and laying out the evidence, so as to serve verification of hypotheses. In the face of a once-in-a-century epidemic, extracting the valuable frontline experience of epidemiological survey would be helpful to accurately handle the epidemic situation, maintain the dynamic COVID-zero status, and respond to other major public health events in the future.