Background : Prevention of myopia has become a public health priority in China. This study is to investigate the prevalence of myopia and vision impairment, and their associated factors in school students in eastern China. Method: In this cross-sectional school-based study of 4804 students from 18 schools ranging from kindergarten to high school, students underwent refraction using non-cycloplegic autorefractor and visual acuity testing using logMAR chart with tumbling E. Myopia was defined as spherical equivalent (SPHE) ≤ -0.5 diopter (D) and uncorrected visual acuity (UCVA) 20/25 or worse. High myopia was defined as SPHE ≤ -6.0 D and UCVA 20/25 or worse. Vision impairment was defined as UCVA 20/40 or worse. Logistic regression models were used to determine factors associated with myopia and vision impairment. Results: Among 4804 children (55% male) with mean age (standard deviation) 12.3 (3.8) years, 3031 (63.1%, 95% CI: 61.7-64.4%) had myopia, 452 (9.4%, 95% CI: 8.6-10.3%) had high myopia, and 2646 (55.1%, 95% CI: 53.7-56.5%) had vision impairment. The prevalence rate of myopia increased with grade in a non-linear manner, 12% in kindergarten, 32% in grade 2, 69% in grade 5, and approximately 90% by grade 10 or above. The prevalence rate of high myopia was relatively low in grade 4 or below (<1.5%), 4-7% in grade 5 to 7, 13-15% in grade 8-9, and >20% in grade 10 to 12. The prevalence rate of vision impairment was 3.7% in kindergarten, 36.6% in elementary school, 76.7% in middle school and 86.5% in high school students. Higher grade (p<0.0001), female (p<0.0001) and higher school workload (p=0.007) were independently associated with higher prevalence rates of myopia and vision impairment, while higher grade (p<0.0001) and higher school workload (p<0.0001) were independently associated with higher prevalence of high myopia. Conclusion: Prevalence of myopia and vision impairment was high among Chinese school students and increased with grade in a non-linear manner, reaching alarming high in high school students accompanied by high prevalence of high myopia. Increasing study burden on school students at younger age plays an important role on the higher prevalence rate of myopia and vision impairment.