The present application provides an oven drying apparatus and a coating device. The oven drying apparatus comprises an oven drying chamber and a heating assembly. The oven drying chamber is equipped with a first oven drying side having a plurality of first air inlet portions for fluid medium to enter the oven drying chamber. The heating assembly is disposed on the first oven drying side. The first oven drying side is further provided with at least one air return portion provided between two adjacent first air inlet portions, and the air return portion being configured for fluid medium in the oven drying chamber to be discharged from the oven drying chamber. The arrangement of an air return portion between two first air inlet portions can discharge fluid medium between the two first air inlet portions and take away the heat, thus avoiding accumulation of heat between the two first air inlet portions.