Air knife coater is mainly composed by the eagle beak knife, feeding roll, pressing roll, metering rod, backing roll, air separator, draft fan for separator, high pressure fan and frame etc. This coating device is characterized by a short distance between the air knife backing roll and the feeding roll, and the coated paper is less water migrated and wrinkled after the metering rod. It has the advantages of compact structure, wide application range, convenience to adjust the coating weight and so on.