Objective:To explore the incidence of hepatitis B virus (HBV) reactivation in the population with HBV associated liver cancer after receiving programmed death receptor 1 (PD-1) inhibitors combined with targeted therapy, and the prognostic differences between HBV reactivation and non reactivation populations during this treatment.Methods:A retrospective analysis was conducted on patients with primary liver cancer who received PD-1 inhibitor combined with targeted drugs treatment at the Zhongshan Hospital, Fudan University (Xiamen Branch) from January 2019 to June 2021. Clinical data such as age, sex, liver function status, cirrhosis, HBV DNA level, alpha fetoprotein, tumor stage, anti-tumor program and anti HBV program, tumor treatment response, progression free survival (PFS), and total survival (OS) were collected for t test, χ 2 test and Kaplan-Meier survival analysis. Results:A total of 66 enrolled patients were enrolled, of which 17 cases experienced HBV reactivation, with an incidence rate of 25.76%; The rates of HBV reactivation at 3 months, 6 months, 1 year, 2 years, and 3 years were 6.06%(4/66), 12.12%(8/66), 19.70%(13/66), 22.73%(15/66), and 25.76%(17/66), respectively. There was no significant difference between the HBV reactivation group and the non HBV reactivation group in age, sex, liver function status, cirrhosis, HBV DNA level, alpha fetoprotein, tumor stage, anti-tumor and anti HBV programs, objective response rate (ORR) and disease control rate (DCR) (all P>0.05). However, the PFS and OS of the HBV reactivation group were significantly lower than those of the non HBV reactivation group, at 4.00 months vs 8.50 months ( P=0.002) and 12.90 months vs 19.77 months ( P=0.014), respectively. Conclusions:Patients with primary live cancer who receive PD-1 inhibitor combined with targeted therapy are at risk of HBV reactivation, and those who experience HBV reactivation have significantly poorer tumor progression and survival prognosis compared with non HBV reactivated patients.