The invention relates to a fluorescence in-situ hybridization technology, and discloses a fluorescence in-situ hybridization method capable of improving covariance. The fluorescence in-situ hybridization method capable of improving covariance comprises the steps of slide specimen preparation, probe and chromosome covariance and hybridization, washing and dyeing after hybridization, and signal detection. According to the fluorescence in-situ hybridization method capable of improving covariance disclosed by the invention, a method of probe and chromosome covariance and hybridization is adopted on the basis of the prior art, the operation is simple, the reaction steps are reduced, experimental time is shortened, and a toxic and teratogenic denaturant does not need to be used, thus decreasing experimental cost, and avoiding the harm of the denaturant to experimental operating personnel and environment. The invention provides a fluorescence in-situ hybridization method capable of improving covariance, which is accurate in location, high in sensitivity, high in experimental efficiency, good in stability, simple to operate, and has environment-friendly effect.