The invention relates to a method for testing the explosion limit of a liquid mixture. The problem that in the prior art, a testing result is inaccurate is mainly solved. According to the technical scheme, the method for testing the explosion limit of the liquid mixture is adopted, a liquid mixture explosion limit testing device is adopted for carrying out a liquid mixture explosion limit test, a sample is added to a sample adding cup of the testing device, the temperature of the sample adding cup and a constant-temperature chamber is controlled, and concentration of mixed gas of the gas phase liquid to be tested and air is controlled by controlling the temperature and volatilization time; then ignition is carried out for testing, a testing result is observed through an observation window, the problem is solved well, and the method can be used for testing the explosion limit of the liquid mixture.