We described a 44-year-old man developing dermatomyositis (DM) and nephrotic syndrome (NS). Renal biopsy revealed diffuse proliferative glomerulonephritis (DPGN) with depositions of immunoglobulin and complements. A combination therapy of steroid and cyclophosphamide (CTX) was found very effective for the patient. Chronic glomerulonephritis is rare in DM. In our review of related literature, membranous glomerulonephritis (MN) is the main type of glomerular lesion, another type is mesangial proliferative glomerulonephritis (mesPGN). Here we reported a case of DM associated with DPGN developing NS, which was not found in existing literature. Although glomerulonephritis is uncommon in patients with DM, renal pathology is not as simplex as previously thought, and treatment with steroid or/and cytotoxic drugs is favorable for prognosis.