The utility model belongs to the field of building, relates to a roof snow melting system, particularly to a roof snow melting system employing smoke waste heat and aims to solve the problem that the conventional roof snow removing method is high in cost and dangerous for workers. The roof snow melting system comprises an upper face plate, a lower face plate, a smoke filtering plate and a ridge smoke filtering and gathering cap. The upper face plate and the lower face plate are vertically parallelly arranged on the roof. The lower surface of the lower face plate is combined with the roof to form a first smoke channel. The lower surface of the upper face plate is combined with the upper surface of the lower face plate to form a second smoke channel. The ridge smoke filtering and gathering cap is mounted at the roof. The first smoke channel and the second smoke channel are communicated with an inner chamber of the ridge smoke filtering and gathering cap. The smoke filtering plate is arranged in the second smoke channel. A smoke inlet of the first smoke channel is connected with an indoor smoke exhaust channel.