To carry out genetic analysis for 21 patients with methylmalonic acidemia (MMA) and provide genetic counseling for their families. Next generation sequencing (panel) was used to detect the pathogenic variants underlying the disease. In total 29 variant sites of MMUT, MMAA, MMUT were identified in the 21 patients, with common variants including c.323G>A (10%), c.917C>T (10%), c.984delC (10%) of MMUT gene, and c.609G>A (45%), c.80A>G (10%) , c.567dupT (10%) of MMACHC gene. Among these, c.2000A>G of MMUT, c.298G>T of MMACHC and c.734-7A>G of MMAA gene were unreported previously. Genetic testing for MMA patients can clarify the cause of the disease and provide a basis for the clinical diagnosis. Discovery of novel variants has enriched the mutational spectrum of MMA.