Objective: To clarify the importance and practical significance of the standardized rate in primary healthcare work by comparing the differences in the prevalence of myopia in districts in Beijing before and after standardization. Methods: This study recruited a total of 41 029 students from 107 primary and secondary schools and 35 kindergartens from the 16 districts of Beijing municipality. All participants underwent distance vision and refractive testing. The presence of myopia was defined as naked eye vision of <5.0 and non-ciliary muscle paralysis under computer optometry with a spherical equivalent objective refractive error of <-0.50 diopters (<-0.50 D). The student composition outlined in the 2018-2019 Beijing Education Development Statistics Summary was used as a standard group to standardize the prevalence of myopia in students from various districts of Beijing. The difference in the pre-and post-standardization rates was used to compare the change in myopia in each district before and after standardization. Results: In 2018, the prevalence of myopia in students from Beijing was 57.3%. Stratified by school period, the prevalence of myopia in preschool, primary school, junior high school, ordinary high school, and vocational high school students was 12.1%, 38.4%, 77.2%, 88.3%, and 73.1%, respectively. Although the prevalence of myopia in Daxing District was the highest both before and after standardization, the difference in the prevalence rate was 13.8 percentage points. The prevalence of myopia in Miyun District was the lowest before standardization. However, after standardization, the prevalence of myopia was lowest in Huairou District. Conclusion The prevalence of myopia among Beijing students is generally high. Before and after standardization, the prevalence of myopia in different districts was quite different. The results show that, in practice, the standardized prevalence can reveal the true epidemiological characteristics of specific disease.