The reports of 1q25-32 deletion cases are rare. We reported here an 11-year-old Chinese Han female with an interstitial 1q25 deletion displaying mental retardation, clinodactyly of the 5th finger and minor facial anomalies. Notably, the patient did not present growth retardation which is quite common in patients with 1q25-32 deletion encompassing LHX4. The heterozygous deletion in this patient was characterized as 46,XX,del(1)(q25.2-q31.3) with a length of 20.5 Mb according to SNP-array test results. STRP (Short Tandem Repeat Polymorphism) analysis of the family trio indicated the genomic abnormality was de novo with paternal origin. After a genotype-phenotype analysis, we proposed here the loss of a 3.1 Mb critical region including 24 genes within 1q25.2 (chr1:174.5-177.6 Mb, build 36) may account for the mental retardation in patients with 1q25-32 deletion.