Objective: To explore the association between alanine aminotransferase (ALT) levels and cardiac structure in childhood, so as to provide scientific evidence to promote childhood cardiac health. Methods: Data were obtained from the baseline survey of the "Huantai Childhood Cardiovascular Health Cohort Study" conducted from November 2017 to January 2018. A total of 1 340 children with complete data were included in the study. Demographic information and lifestyle factors were collected through questionnaires. Physical examinations and blood biochemical tests were performed to obtain children s body mass index (BMI), blood pressure, fasting plasma glucose (FPG), triglyceride (TG), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), and ALT levels. Further, cardiac structural indicators such as left ventricular end diastolic diameter (LVDD), left ventricular end systolic diameter (LVSD), left ventricular posterior wall thickness (LVPWT), and interventricular septal thickness (IVST) were measured by ultrasound. Relative wall thickness (RWT), left ventricular mass (LVM), and left ventricular mass index (LVMI) were calculated. Multivariate linear regression models were used to analyze the relationship between ALT levels and cardiac structural indicators. Restricted cubic spline (RCS) models were used to explore the dose response relationship between ALT levels and cardiac structural indicators. Results: There were significant differences in LVDD, LVSD, IVST, LVPWT, LVM, LVMI and RWT in different ALT level groups ( F =78.69, 60.08, 72.86, 74.89, 83.14, 36.70, 20.46， P <0.05). Multivariate linear regression analysis showed that ALT levels were positively associated with LVDD, LVSD, IVST, LVPWT, LVM, and LVMI ( β =0.10, 0.20, 0.16, 0.16, 0.23, 0.18， P <0.05) after adjusting for potential covariates. The RCS showed a linear dose response relationship between ALT levels and LVDD, LVSD, IVST, and LVMI after adjusting for potential covariates ( P non linear >0.05). In contrast, a non linear doseresponse relationship was found between ALT levels and LVPWT and LVM ( P non linear <0.05). Conclusions ALT levels in childhood are positively associated with the majority of cardiac structural indicators, presenting a linear or non linear dose response relationship.