A method for identifying the genetic relatedness of Liriodendron hybrids is provided, including: 1) extracting DNA of Liriodendron hybrid leaves; 2) performing PCR detection; and 3) identifying the genetic relatedness of Liriodendron spp. according to the size of PCR products amplified with different primers. A special kit for the method for identifying the genetic relatedness of Liriodendron hybrids is further provided, including a primer pair 18.2 and a primer pair 700. Moreover, an application of a special kit for identification of the genetic relatedness of Liriodendron hybrids is provided.