Objective:To investigate the clinical characteristics and prognosis of Philadelphia (Ph) chromosome-positive chronic myeloid leukemia (CML) patients with additional chromosomal abnormalities.Methods:The data of 351 CML patients with Ph-positive in the Affiliated Hospital of Qingdao University from January 2009 to January 2019 were retrospectively analyzed. The bone marrow chromosomal karyotype analysis of all patients was performed by using R-banding technique. The clinical characteristics and karyotype of Ph-positive CML patients with additional chromosomal abnormalities at initial diagnosis were summarized, and Kaplan-Meier was used to analyze the differences in overall survival (OS) of patients with different karyotypes.Results:Among 351 patients with Ph-positive CML, 32 (9.1%) cases had variant translocation. At initial diagnosis, 47 cases had additional chromosomal abnormalities including 29 cases in chronic phase accounting for 9.15% (29/317) of all patients in chronic phase, 3 cases in accelerated phase accounting for 25.00% (3/12) of all patients in accelerated phase, 15 cases in blast crisis accounting for 68.18% (15/22) of all patients in blast crisis; there was a statistically significant difference in the chromosomal abnormalities rate of all different phases ( χ2=50.799, P<0.05). Among 47 Ph-positive CML patients with additional chromosomal abnormalities, 13 patients had complex karyotypes with more than 3 additional chromosomal abnormalities, the proportion of complex karyotypes in chronic phase, accelerated phase and blast crisis was 13.79% (4/29), 33.33% (1/3) and 53.33% (8/15), respectively, and the difference was statistically significant ( χ2=9.26, P<0.05). The study showed that the most common additional chromosomal abnormalities in chronic phase were double Ph (48.28%, 14/29) and -Y (10.34%, 3/29), while the most common chromosomal abnormalities in the blast crisis were +8 (26.67%, 4/15) and double Ph (26.67%, 4/15). Kaplan-Meier survival analysis showed that at initial diagnosis the OS time of patients with additional chromosomal abnormalities was worse than that of those with the non-additional chromosomal abnormalities group ( χ2 = 61.138, P<0.05). The OS of patients with complex karyotypes for Ph - positive CML patients with additional chromosomal abnormalities at initial diagnosis was worse than that of patients with non-complex karyotypes, and the difference was significant ( χ2 = 4.945, P < 0.05). Conclusions:The additional chromosomal abnormalities is closely related to the progression of CML, and the prognosis of CML patients with additional chromosomal abnormalities is poorer than that of patients with only Ph translocation. Moreover, the more complex the additional chromosomes are, the more likely blastic changes are, and the poorer prognosis. And additional chromosomeal abnormalities during the treatment of CML patients may also lead to the progression of blastic changes.