Acid sphingomyelinase deficiency (ASMD), also known as type A and B Niemann-Pick disease, is a group of intra-lysosomal lipid storage diseases caused by mutations in the SMPD1 gene that decrease acid sphingomyelinase activity or even cause deletion, resulting in abnormal deposition of sphingolipids. This disease can be diagnosed by bone marrow aspiration, pathological biopsy, acid sphingomyelinase activity measurement and SMPD1 gene testing. In recent years, with the rapid progress of molecular diagnostic techniques, new insights have been gained in the laboratory diagnosis of ASMD by means of molecular genetic tests, biomarkers and acid sphingomyelinase activity assay. This article will review the diagnostic progress of ASMD, aiming to reduce the misdiagnosis and leakage of the disease and improve the clinicians′ understanding of the disease.