The invention discloses a method for detecting adulterated milk by virtue of a fluoride ion electrode. Fluoride ions have very active chemical properties and widely exist in various environments; and the most sensitive and simple method for determining the content of the fluoride ion at present is an electrode method, and the electrode method has the advantages that equipment is simple, convenient to carry, low in sample dosage, very simple to operate and very sensitive, can be used for processing multiple samples once and particularly can be operated in a working site. The fluorine content in milk is extremely low and cannot be generally detected, and milk has a very good barrier action to fluorine, so that a high-fluorine phenomenon does not appears in milk of some dairy cows drinking high-fluorine water; generally, normal milk in buffer liquid cannot be read, but once an object is adulterated, fluorine in the adulterate object can be detected by virtue of a fluoride electrode, and adulteration in any manner can be detected; if the adulterate object such as the fluorine content of water is known, the water adulteration amount can be calculated through the reading of the electrode; and the fluoride ion electrode has qualitative and quantitative detection functions.