Objective: Femoral neck fractures(FNFs) patients from 2018 to 2020 were classified according to the new AO classification. To observe the proportion of new AO classification and provide reference for improving the upper age limit of internal fixation(IF) treatmentMethods: In this study, patients with femoral neck fracture hospitalized in Xi 'an Honghui Hospital from January 2018 to January 2021 were divided into four groups according to age: the young group (≤44 years old), the middle-aged group (45-59 years old),the young elderly group (60-74 years old), and the elderly group (≥75 years old) to analyze age,sex,side,injury mechanism,new AO classification and other features . A total of 2071 patients were included for analysis.Results: There were 742 males (35.8%) and 1,329 females (64.2%).There were 1,106 patient s(53.4%) on the left side and 965 on the right side (46.6%).There were 1781 patients of low energy injury (86%) and 290 patients of high energy injury (14%), and the main injury mechanism was falling.The number of patients with femoral neck fracture in each year was 719 patients in 2018, 694 patients in 2019, and 661 patients in 2020, respectively. The number of patients showed a decreasing trend year by year, and the gender ratio and injury mechanism showed no significant trend of change. In the age group, the proportion of the young group was increasing year by year.Among the new AO classification, there were 1023 patients of B1.3, accounting for the highest proportion of 49.4%.The proportion of B2.2 was the highest in the young group (32.4%) .B1.3 and B2.2 were the main types in the middle-aged group, accounting for 31.7% and 32.0, respectively.B1.3 was dominant in the young elderly and elderly group (47.1% and 63.4%, respectively).Conclusion: The new AO classification is more detailed and practical. 1/3 of the fracture types of middle aged and young elderly people may achieve satisfactory results through IF.Level of evidence: III.