Background: To investigate the association of 10 genetic variations and 10 environmental factors with myopia of different severities in different age groups of children and adolescents in northeast China. Methods: Parental history and genetic testing for myopia-related susceptibility genes were carried out in a cohort of children and adolescents aged 2–17 years. In addition, 10 single nucleotide polymorphism (SNP) sites for genotyping and 10 environmental risk factors were selected, and the differences between site variation and environmental factors in different age groups with different degrees of myopia were explored. Results: A total of 2497 volunteers were recruited, including 2023 myopes and 474 non-myopes in the control group. From the cohort, 1160 subjects were sequenced for myopia SNP sites. Compared with the non-myopic group, the myopia of parents, outdoor activity less than 60 min per day, and a high-sugar diet were risk factors for developing myopia. Two syntrophin beta 1 (SNTB1) sites, rs4455882 and rs6469937 were found to be significantly associated with moderate myopia; fibroblast growth factor 10 (FGF10) rs339501 was significantly correlated with high myopia; and insulin-like growth factor 1 (IGF1) rs5742714 was significantly correlated with different degrees of myopia in the age group of 6 years. Finally, the FGF10 gene rs339501 SNP was significantly associated with moderate myopia and mild myopia in the 6- to 12-year-old age group. Conclusions: Our results indicate that myopia is affected by both environmental and genetic factors. To prevent and control myopia, attention should be paid to the parental history of myopia, a high-sugar diet should be avoided, and outdoor time should be adjusted according to the average daily sunshine. In addition, it is necessary to pay attention to the increased risk of myopia in school-age children caused by SNTB1 rs4455882, FGF10 rs339501, and IGF1 rs5742714.