The study aims to understand the current status of the knowledge，attitude and practice（KAP） regarding frailty assessment among primary doctors in Nanjing and to analyze its influencing factors. A self - designed questionnaire was used to conduct an online survey targeting primary doctors from 12 districts in Nanjing. A total of 105 valid questionnaires were collected. The total average score of KAP of the primary doctors 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 knowledge of frailty，the access of sources to frailty - related knowledge，and the frequency of frailty assessment were influencing factors for the knowledge dimension score of frailty assessment among primary doctors（P＜0.05）. There was a statistically significant difference in the attitude dimension score of frailty assessment between male and female primary doctors（P＜0.05）. Different sources of knowledge acquisition were influencing factors for the practice dimension score of frailty assessment among primary doctors（P＜0.05）. In conclusion，primary doctors have a relatively positive attitude towards frailty assessment，but there is room for improvement in their knowledge level and practice capability.