To analyze the clinical features and genetic basis of three children with mental retardation, language impairment and autistic features due to de novo variants of FOXP1 gene.Clinical data of the children were collected.Trio-whole exome sequencing was carried out for the children and their parents. Pathogenicity of the variants was analyzed through bioinformatics prediction.All of the children had various degrees of mental retardation in conjunct with language deficit, global developmental delay, abnormal behavior and peculiar facial features, among whom two also developed autism spectrum disorders. The results of genetic testing showed that all three children harbored de novo variants of the FOXP1 gene, namely c.613_c.614delCTinsTA, c.1248delC and c.1393A>G. Two of these were frameshift variants and one was missense variant, which were all rated as pathogenic based on the guidelines of the American College of Medical Genetics (ACMG). Database search suggested that c.613_c.614delCTinsTA and c.1248delC were unreported previously.For the three children from unrelated families with mental retardation in conjunct with language deficit, global growth delay, abnormal behavior and peculiar facial features, the c.613_ c. 614delCTinsTA, c.1248delC and c.1393A>G variants of the FOXP1 gene may be the pathogenic factors. Above cases have further expanded the genotype-phenotype profile of FOXP1 deficiency syndrome.