Mucopolysaccharidosis type Ⅰ was a rare inherited metabolic disorder caused by a deficiency of alpha-L-iduronidase, resulting in the incomplete degradation of glycosaminoglycans that accumulate in lysosomes, leading to tissue damage and organ dysfunction. The main treatment options for mucopolysaccharidosis type Ⅰ were hematopoietic stem cell transplantation and enzyme replacement therapy. Patients who did not receive early replacement therapy often struggle to survive into adulthood, and cases of enzyme replacement therapy initiated in adulthood were extremely rare. This article summarized and analyzed the clinical data and enzyme replacement therapy experiences of two adult mucopolysaccharidosis type Ⅰ patients. Through the two cases analysis and literature review, we tried to enhance understanding of the disease characteristics and the efficacy and adverse reactions associated with enzyme replacement therapy, ultimately aiming to benefit the mucopolysaccharidosis type Ⅰ patients. Both patients were adult male and more than twenty years old. And they had the different economic backgrounds. They both presented symptoms at one year old and had normal intellectual development. Clinical features included typical manifestations of mucopolysaccharidosis type Ⅰ such as short stature, coarse facial features, and joint contractures. They were diagnosed with the intermediate form of mucopolysaccharidosis type Ⅰ, with significantly reduced alpha-L-iduronidase activity. The alpha-L-iduronidase gene mutations were as follows: Patient 1 presented c.2T>C, p.M1? /c.1898C>T p.S633L, and Patient 2 had c.532G>A, p.E178K/. Patient 1 received laronidase injections for six months, while Patient 2 was treated with laronidase for thirty months, with both showing varying degrees of symptom improvement. Following their initial dose, both patients experienced fever, nausea, vomiting, diarrhea, and rash, but these symptoms were alleviated with symptomatic treatment. Laronidase therapy demonstrated clear efficacy in adult patients with mucopolysaccharidosis type Ⅰ, with most adverse reactions occurring during the first injection stage, including fever, rash, and gastrointestinal symptoms, all of which were manageable. Early diagnosis and specific treatment for this condition are crucial, and such therapies can be implemented in regular domestic hospital settings.