This study aimed to evaluate the relevant factors of postoperative avascular necrosis of the femoral head (AVN) in children with femoral neck fracture. This study retrospectively analyzed the clinical data of 28 children with femoral neck fractures treated at our center between July 2016 and January 2019. The average age was 9.3 (range, 4.4-14) years with 75% male participants. Fracture classification was based on the Delbet classification: there were four, seven, 15, and two cases of type I, II, III, and IV fractures, respectively. Displacement degree was based on the Garden classification. Sixteen cases had insignificant displacement (Garden types I and II), six had medium displacement (Garden type III), and six had significant displacement (Garden type IV). There were six early (≤24 hours) and 22 delayed (>24 hours) surgeries. Twenty-three patients had satisfactory reduction, and five had unsatisfactory reduction. The mean postoperative follow-up period was 15.7 (range, 12-36) months. Follow-up was evaluated using the Ratliff scoring standards. The correlation between age, fracture classification, displacement degree, surgery timing, reduction quality, and other factors and AVN occurrence was statistically analyzed. Among 28 children, AVN was found in six cases. There were statistically significant differences in displacement degree (P = 0.001) and reduction quality (P = 0.001), while the occurrence of AVN did not significantly differ with sex (P = 0.117), age distribution (P = 0.218), fracture classification (P = 0.438), surgery timing (P = 0.255), and mechanism of injury (P = 0.436). The results of logistic regression analysis showed that displacement degree was a relevant risk factor (P = 0.049, odds ratio [OR] = 8.391, 95% confidence interval [CI]: 1.004-70.117), while reduction quality was not (P = 0.075, OR = 14.536, 95% CI: 0.757-278.928). Although the development of AVN in children with femoral neck fractures may be related to many factors, the results of this research suggest that there is a significant correlation between displacement degree and AVN occurrence.