The invention discloses a pit type oven, solving the technical problem that the traditional equipment influences the straightness of products when carrying out a subsequent vulcanization process on a large-scale polyurethane high-efficiency classifying screen. The pit type oven comprise a pit (9), an oven (8) and a programmable controller for controlling the oven; a motor (12) is connected with a blower (13) together; an output port of an electric heater (14) is connected with an input port of the blower (13) together; an output port of the blower (13) is communicated with a hot air input port of the oven (8); a hot air output port of the oven (8) is communicated with an input port of the electric heater (14); the lower half part of an oven body of the oven (8) is arranged in the pit (9); a side opening door (6) is arranged on one lateral surface of the upper half part of the oven body of the oven (8); and a top cover (4) of the oven (8) is a movable top cover. The invention saves the operation space and ensures the straightness of the products.