The study aims to understand the current status of the knowledge-attitude-practice (KAP) regarding frailty assessment among primary care physicians in Nanjing, and to analyze the factors influencing it. From November to December 2023, we designed a survey and conducted a cross-sectional study online among primary care physicians across 12 districts in Nanjing, obtaining 105 valid questionnaires with a high response rate of 94.6%.The total average score of KAP of the primary care physicians on the frailty assessment was (69.09±12.76), with an average score of (14.70±4.08) on the knowledge dimension, (22.16±4.22) on the attitude dimension and (32.22±7.17) on the practice dimension. The results of multiple linear regression analysis showed that the level of understanding of frailty, the sources of acquiring frailty-related knowledge, and the frequency of frailty assessment were influencing factors for the knowledge dimension score of frailty assessment among primary care physicians (P<0.05). There was a statistically significant difference in the attitude dimension score of frailty assessment between male and female primary care physicians (P<0.05). The source of acquiring frailty-related knowledge was an influencing factor for the practice dimension score of frailty assessment among primary care physicians (P<0.05). In conclusion, Primary care physicians have a relatively positive attitude towards frailty assessment, but there is room for improvement in their knowledge level and practice capability.It is urgent to improve the training on frailty assessment and management for primary care physicians, enhance their competency in their positions, and translate research on frailty assessment and management in the elderly into practice.