The invention discloses a kit for detecting a relative expression index of a leukemia BCR/ABL (m-bcr) fusion gene. The kit comprises a red blood cell lysis solution, TRIzol, chloroform, absolute ethanol, ReverTraAceqPCRRTKit, a detection system PCR (Polymerase Chain Reaction) reaction solution, a positive control sample and a negative control sample, and is characterized in that the detection system PCR reaction solution comprises THUNDERBIRDqPCRMIX, upstream and downstream primers m-bcr-F and m-bcr-R and a probe m-bcr-Probe for detecting target genes, and primers ab1-F and ab1-R and a probe ab1-Probe for detecting internal reference genes Ab1, wherein the m-bcr-F is GGCGCCTTCCATGGAGAC, the m-bcr-R is TCCTTGGAGTTCCAACGA, the m-bcr-Probe is TTTGAGCCTCAGGGTCTGAGTGAA, the ab1-F is GCCGTGAAGACCTTGAAGGAG, the ab1-R is ATGATATAGAACGGGGGCTC, and the ab1-Probe is FAM-ACCTGGTGCAGCTCCTTGGG-TAMRA.