The invention provides a preserving fluid for biological sample nucleic acid detection and an application thereof. The preserving fluid is composed of a nuclease inhibitor, a surfactant, a chelating agent and a buffer solution. The preserving fluid is mixed with a solid sample or a liquid sample to denature proteins, inactivate pathogens, and inactivate DNA and RNA nuclease. The pathogens are inactivated, so the safety of a potential high-infectivity clinical sample is greatly improved, and good protection is formed for surrounding personnel and downstream operating personnel of the sample; the DNA and RNA nuclease is inactivated, so that the content and integrity of DNA and RNA in the sample are kept in a sampling state to the maximum extent, and the strict requirements on the aspects oftemperature, time and the like of clinical sample transportation and storage are reduced. The preserving fluid can be used for clinical high-infectivity nucleic acid detection of biological samples, and the biological samples comprise throat swabs, body fluids, lavage fluids, whole blood, whole blood cells, serum or plasma.