Meibomian gland dysfunction(MGD)is mainly characterized by terminal duct obstruction and/or qualitative/quantitative changes in the glandular secretion, resulting in the alteration of tear film and ocular surface diseases. It covers several meibomian gland diseases ranging from congenital to acquire. With the progress of clinical research, recent studies indicate there are many risk factors related to MGD, including ophthalmic diseases, systemic diseases, therapeutic approaches(topical/systemic medication, surgery)and even environmental factors. Thus, a proper understanding of the various risk factors acting on MGD will be helpful to the clinical diagnosis and treatment of MGD.