Autism, with a global morbidity of approximately 0.6% annually, significantly burdens on families and society. A predominant characteristic among autistic children is intestinal dysfunction, generating nutrient absorption issues. This often causes vitamin and mineral deficiencies, which significantly impacts neurological development. To address this, we have developed a comprehensive nutritional supplement containing compound vitamins, minerals, and gut bacteria. The aim of this study is to investigate the behavioral effects of this supplement on autism rats. The supplement formulated in this study encompasses compound vitamins, minerals, and intestinal bacteria. The autism offspring model (VPA model) was established through intraperitoneal injection of sodium valproate into pregnant rats. Behavioral assessments, gastrointestinal microbiota analysis, and brain development evaluations were conducted to assess the effects of the supplement on VPA offspring rats. A nutritional supplement enriched with vitamins (VB6, VB12, VC, VD, folic acid), minerals (calcium, magnesium), and bifidobacteria was prepared. Open field experiments demonstrated a 3-mo supplementation intervention effectively alleviated anxiety symptoms and enhanced curiosity levels in VPA offspring. The bead embedding experiment revealed the supplementation significantly improved stereotypical behaviors in VPA offspring. The nesting experiment showed a 3-mo supplementation intervention effectively enhanced cognitive abilities in VPA offspring rats. The three-box social experiment demonstrated the supplementation improved social novelty and tendency in VPA offspring. Analysis of gastrointestinal microbiota revealed the supplementation modulated the gut microbiome, promoting better nutrient absorption and overall health. Our findings suggest the comprehensive nutritional supplement, containing compound vitamins, minerals, and gut bacteria, effectively alleviates core symptoms of autism in rats. This study provides valuable insights into the potency of nutritional interventions in improving the quality of life for autistic individuals. Future research is warranted to further explore the mechanisms underlying these observed benefits and to assess the long-term effects of this supplement in larger clinical trials.