Objective To survey the prevalence of potentially inappropriate medication (PIM) in very old hospitalized patients by combining the 2019 American Geriatrics Society (AGS) Beers Criteria and 2014 Screening Tool of Older Persons′ Prescriptions (STOPP) Criteria, and investigate the influencing factors. Methods A retrospective analysis was carried out on the 1023 inpatients aged ≥ 80 years in the Second Medical Center of Chinese PLA General Hospital from January 2015 to December 2020. PIM prevalence was assessed based on the 2019 AGS Beers Criteria and 2014 STOPP Criteria. SPSS statistics 22.0 was used to perform the statistical analysis. Logistic regression analysis was employed to analyze the influencing factors for PIM. Results According to the 2019 AGS Beers Criteria and 2014 STOPP Criteria, the prevalence of PIM was 79.3% (811 cases) and 59.1% (605 cases), respectively. And the consistency of the 2 screening criteria was quite low (Kappa=0.238, P<0.001). The most frequently prescribed PIM was Benzodiazepines according to the both criteria. Screening Tool to Alert to Right Treatment (START) Criteria found that the potential prescribing omission (PPO) incidence was 52.9% (541 cases). Logistic regression analysis indicated that age, Charlson comorbidity index and number of concomitant medications were risk factors for PIM. Conclusion The prevalence of PIM is quite high in the very old hospitalized patients. Combining Beers and STOPP criteria are effective to enhance the detection of PIM.