Objective: To investigate the association of serum alanine aminotransferase (ALT) with left ventricular hypertrophy (LVH) in adolescents, and to provide scientific evidence for the early screening and intervention strategy of cardiac structure damage. Methods: Data were obtained from the third follow up survey (October 2023) of the "Huantai Childhood Cardiovascular Health Cohort Study", including 1 156 healthy adolescents aged 12-17 with complete information. The sample population was stratified into low ( Q 1 group), medium ( Q 2 group), and high ( Q 3 group) ALT levels based on tertiles within the same gender and age groups. Inter group comparisons were conducted using analysis of variance and trend test. A multivariate Logistic regression model was used to analyze the association between ALT levels and LVH, and stratified analyses were performed by gender and age groups. Results: With the increase of ALT quantile level, the detection rate of LVH showed an increasing trend ( Q 1: 3.7%; Q 2: 10.6%; Q 3: 16.7%, Z= 5.89 , P <0.01). After adjusting for potential covariates, compared with the ALT group ( Q 1), the group ( Q 3) increased the risk of developing LVH in adolescents ( OR=2.09, 95%CI =1.21-4.12). Stratified analyses by age and sex showed a significant association only in boys and younger individuals aged 12 to 14 years [ OR (95% CI ) were 2.64(1.04-7.67) and 3.24( 1.35 -9.06), both P <0.05)]. Conclusion Elevated serum ALT levels are associated with an increased risk of LVH in adolescents, and early detection and control of abnormal liver enzyme levels can help reduce early vascular structural damage and prevent adverse cardiovascular events.