Abstract: Through the study of the millimeter wave transparent window material characteristics, the design of singlelayer and multi-layer (three layers, five layers) transparent window is carried out, the influence of port matching on window transmission loss and the introducing noise are analyzed. Concurrently, the trial production of Ka-band transmission window and introducing noise test are carried out, the experimental results show that the transmission window designed by multilayer dielectric matching, within the working frequency band, transmission loss is better than 0. 2 dB, introducing equivalent noise temperature Te is ≤14K, the port reflection of the window is effectively reduced, at the same time, the matching bandwidth is greatly expanded.