Abstract: An over-the-range microwave oven and a ventilation passage system of the same are provided. The over-the-range microwave oven includes an outer casing defining a cooking cavity and an exhaust passage in the outer casing, the exhaust passage defining an inlet formed in a base plate of the outer casing and an outlet; and a baffle plate disposed below and facing the base plate, in which the baffle plate and the base plate are spaced apart from each other to form a smoke collection cavity between the baffle plate and the base plate.