Autism spectrum disorder (ASD) is a neurodevelopmental disorder with a strong genetic component that is becoming increasingly prevalent. The identification of plasma molecular biomarkers may provide potential insights into ASD and aid in early diagnosis. In this study, we characterized the metabolomic profiles of ASD children using blood spot samples collected at the Children's Hospital of Zhejiang University School of Medicine from children with ASD (n = 43) and typically developing (TD) children (n = 43). Our results highlight differences between children with ASD and TD controls. We identified possibly associations between ASD and a variety of metabolites, including carnosine (Car), glutaric acid, histidine (His), succinic acid, tryptophan, glutamine (Gln), asparagine, guanidinoacetic acid, sarcosine, kynurenine, glutamic acid (Glu) and cysteine (Cys). Metabolic pathway analysis demonstrated a possible imbalance in the amino acid metabolism of Glu/Gln, Car/His in ASD children. These findings may provide new insights into the molecular mechanisms that influence ASD risk and have possibility for the discovery of biomarkers.