Abstract: A kind of low noise post-amplifier for UWB cryogenic receiver is designed in this paper, and the simulation and test data are presented. Three-stage MMIC were used in the amplifier, for the gain correction of the amplifier, equalization and attenuation network were used between two chips,it makes the gain flatness effectively, while less influence on noise figure and others . The fabricated LNA has realized the good performance in the range of 1～9GHz, room tempe-rature noise coefficient is less than 2dB, the gain is greater than 35dB, flatness of gain is less than 3.5dB, input and output SWR is less than 2.5 and the power 1dB compression is more than 10dBm.