Objective: To investigate the associations of classroom lighting environment and desk-chair fit rate with the prevalence of screening myopia in primary and secondary school students, so as to provide a scientific basis for education and health administrative departments to implement targeted environmental interventions. Methods: Based on the National 2025 Project for Monitoring and Intervention of Common Diseases and Health Risk Factors among Students, a survey was conducted from September to October 2025. Environmental and common disease surveillance data from 36 primary and secondary schools in Yinchuan City in 2025 were extracted. Using schools as the unit of analysis, multiple linear regression and restricted cubic spline (RCS) models were employed to examine dose response relationships between environmental exposure variables and myopia prevalence, and multilevel mixed effects models were constructed for validation. Results: The overall school level prevalence of screening myopia among students was (58.2±22.0)%, and the compliance rate of desk-chair allocation was 7.8%. After adjusting for school segment, multiple linear regression analysis showed that average desk surface illuminance on the desk surface was positively associated with screening myopia prevalence among primary and secondary school students ( β =0.20, P =0.02). The RCS model revealed a significant non-linear relationship between average desk surface illuminance and screening myopia prevalence ( P-non linear <0.05), with screening myopia prevalence increasing to nearly 40% after the illuminance exceeded the inflection point of 480 lx. The multilevel mixed effects model showed that, after controlling for school clustering effects, each one grade increase in school grade was associated with a 62% higher risk of screening myopia ( OR =1.62); after controlling for individual factors and school random effects, each 100 lx increase in illuminance was associated with a 16% higher risk of screening myopia ( OR =1.16) (both P <0.05). Conclusions Mismatches widely exists in desk-chair dimensions of primary and secondary schools. “High illuminance” may mask the confounding effects of academic burden. Myopia prevention and control should therefore shift from a focus on improving physical infrastructure alone toward comprehensive environmental and behavioral interventions.