The invention discloses a kit, a primer, a probe and a detection agent for detecting tumor gene variation. The kit, the primer, the probe and the detection agent for detecting the tumor gene variationcan be used for detecting tumor driving gene EGFR mutation, KRAS mutation, BRAF mutation, HER2 mutation, MET mutation, EML4-ALK fusion and ROS1 fusion. The fluorescent probe for detecting tumor genevariation, disclosed by the invention, has the advantages that the fluorescent probe is specifically combined with a mutant type DNA template in the PCR process but not combined with a wild type DNA template, so that a mutant type amplification result generates a fluorescence signal, and a wild type amplification result does not generate the fluorescence signal; a final judging result is that themutant type amplification result has a Ct value and the wild type amplification result has no Ct value. The primer and the probe for detecting tumor gene variation, disclosed by the invention, have the advantages of high specificity, simple kit operation, high detection sensitivity and objective and accurate qualitation of tumor gene variation.