Autism Spectrum Disorder (ASD) is a complex neurodevelopmental disorder characterized by deficits in social communication and repetitive behaviours. The gut microbiota plays a pivotal role in the etiology of autism spectrum disorder, and its modulation represents a promising therapeutic strategy to alleviate autism-like behaviours. The purpose of this study was to evaluate the effects of Acer truncatum oil (ASO) on autism-like behaviours in an autistic mouse model, BTBR T+ Itpr3tf/J (BTBR) mice, and to assess the related molecular mechanisms. The juvenile BTBR mice were administered with ASO for 36 consecutive days by gavage. Behaviour tests showed that ASO remarkably alleviated the autism-like behaviours of BTBR mice. In addition, the supplementation with ASO promoted the maturation of oligodendrocytes and suppressed microglial over-activation, and reduced the IL-1 beta and TNF-alpha levels in the hippocampus of the BTBR mice. Oral ASO administration also improved gut microbiota imbalances in BTBR mice by reducing the abundance of the harmful bacterium Mycoplasma and the ratio of Firmicutes to Bacteroidetes. Additionally, ASO decreased the expression of TNF-alpha and IL-1 beta, and increased the levels of ZO-1, claudin-1 and occludin in the intestine, thereby reducing intestinal inflammation and repairing intestinal barrier damage. Our results indicate that ASO has great potential in the treatment of autism, providing theoretical basis for the development of autism drugs.