Objective: To determine the HIV infection of a 13-year-old leukemia patient Wei using molecular tracing technique. Methods: Three blood samples were collected from the persons who were associated with HIV positive blood donation member Lang. The viral load was tested and pol gene was sequenced and analyzed. At the same time using HyPhy2.2.4 and Cytoscape 3.6.1 to establish the molecular network with these 3 samples sequences and other HIV subtypes sequences obtained from Luzhou. Results: The HIV-1 viral load test result of the three patients were: Lang 933 CPS /ml (treated, blood donor), Wei (blood recipitent) 89 813 CPS /ml, Deng (blood recipitent) 85 158 CPS /ml. The subtype of HIV-1 of these three samples were all recombinant HIV CRF01_AE, and the pol gene similarity was 98.8% (Lang and Wei), 99.7% (Lang and Deng), and 99.1% (Wei and Deng), respectively. The gene sequences of the three samples were linked into clusters (the gene distance was less than 0.004). Conclusions The patient Wei with leukemia was infected with HIV-1 due to blood transfusion during the seroconversion period, and the three patients were more likely to be infected with the same HIV-1 strain. It is necessary to popularize the use of high-sensitivity nucleic acid detection method in blood collection and supply institutions, which can effectively improve the safety of blood use.