Objective　To analyze the clinical features and genetic characteristics of mucolipidosis (ML) II and III α / β. Methods　The clinical data of 3 children with ML II and III α / β caused by mutation of GNPTAB gene were retrospectively analyzed, and relevant literatures were reviewed. Results　Two children, aged 8 years and 3 months and 23 months, respectively, were Han nationality males from the same family. Both of them showed different degrees of joint contracture and short stature. The other child was a 19 months old girl, with symptom of growth retardation, shallow orbits, collapsed nose bridges, protruding mouth and low-set ears. She also had a history of repeated respiratory infections. Genetic testing showed that two male children had a compound heterozygous variant of c.1284+1G > T and c.1370C > T (p.Pro436Leu) in the GNPTAB gene. The female child had homozygous variants of c.1090C > T (p.Arg364*) in the GNPTAB gene. The parents of three patients carried heterozygous variants of the GNPTAB gene. Conclusions　Mutations of GNPTAB gene can result in ML II and III α / β that should be differentiated clinically.