Objective: To explore the relationship between serum homocysteine (Hcy), interleukin-5 (IL-5), folate and core symptoms in children with autism spectrum disorders, so as to provide potential biomarkers for early diagnosis and intervention of diseases. Methods: A total of 106 children with autism spectrum disorders and 106 healthy children with matched sex and age in Lu an People s Hospital were enrolled as autism group and healthy group between May 2020 to December 2023. On the day of admission, levels of serum Hcy, IL-5 and folate were detected. The core symptoms in autism group were evaluated by Autism Behavior Checklist (ABC), Wechsler Preschool and Primary Scale of Intelligence-fourth edition(WPPSI-IV), Childhood Autism Rating Scale (CARS) and Social Responsiveness Scale (SRS). The levels of serum Hcy, IL-5 and folate in the two groups were compared by t- test. The relationship between serum Hcy, IL-5, folate and core symptoms in children with autism spectrum disorders was determined by Pearson correlation analysis. Results: The levels of serum Hcy and IL-5 in autism group were (7.48±0.32) μmol/L and (345.77±32.51) pg/mL, higher than those in healthy group [(6.11±0.54) μmol/L, (274.04±25.17) pg/mL], while folate level was lower than that in healthy group [(15.24±3.47) ng/mL, (22.51±4.69) ng/mL], the differences were statistically significant ( t =22.47, 17.96, 12.83, all P < 0.05 ). In autism group, levels of serum Hcy and IL-5 were positively correlated with scores of ABC, CARS and SRS ( r =0.29, 0.53 , 0.54; 0.45, 0.41, 0.50), while negatively correlated with WPPSI-IV score ( r =-0.28, -0.26)(all P <0.05). The folate level was negatively correlated with scores of ABC, CARS and SRS ( r =-0.55, -0.40, -0.25), while positively correlated with WPPSI-IV score ( r =0.41) (all P <0.05). Conclusion Children with ASD show elevated serum Hcy and IL-5 alongside decreased folate,and three markers correlate with core symptoms and intellectual level.