Objective: To investigate the current prevalence of myopia and the progression of the axial length/corneal radius ratio(AL/CR) among primary school students in Jing an District, Shanghai, and to analyze the value of dynamic AL/CR monitoring and elucidate its longitudinal association with myopia progression, so as to provide evidences for supporting myopia prevention and control interventions. Methods: From 2019 to 2023, by using a stratified cluster random sampling method, 17 624 students from two primary schools in Jing an District, Shanghai were selected for annual vision screenings in five consecutive years. Additionally, a retrospective cohort of 480 eligible first grade students identified in 2019 was followed up until 2023. The analysis focused on the myopia prevalence and the trend in the AL/CR. Differences in screening myopia rates across different student groups from 2019 to 2023 were compared using the Chi square test. The trends in myopia rates were analyzed using the Chi square trend test. The Kruskal-Wallis H test was employed to compare AL/CR and its annual increment across groups. A linear mixed effects model was used to identify factors influencing AL/CR, and a time dependent Cox regression model was developed to predict the risk of myopia onset. Results: From 2019 to 2023, the screening myopia rates were 36.65%, 38.31%, 40.47%, 39.56%, and 39.76% for each respective year. Cohort analyses revealed Grade 5 girls had significantly greater AL/CR increments than boys ( Z =-2.05, P <0.05). Linear mixed models identified baseline AL/CR ( β =1.051, 95% CI =1.012-1.091), grade level ( β =0.040, 95% CI =0.038- 0.042 ), and first year AL/CR increment ( β =0.788, 95% CI =0.733-0.843) as primary determinants (all P <0.01). Boys showed slower AL/CR progression than girls ( β =-0.003, 95% CI =-0.005 to-0.001, P <0.01). The time dependent Cox model demonstrated that both baseline AL/CR ( Z =3.40) and its time varying effect ( Z =10.41) significantly predicted myopia risk(both P <0.01). The effect of AL/CR on myopia risk significantly increased with follow up time, and the growth rate exceeded a linear progression pattern. Conclusions AL/CR progression is primarily driven by baseline values and grade advancement, with slower progression in boys. Dynamic AL/CR monitoring outperforms baseline measurements in predicting myopia progression. Students with rapid AL/CR increments require early intervention.