Abstract: Radio astronomy is a subject of studying cosmic objects by receiving and processing radio waves. Microwave receiver is the core receiving equipment of radio astronomy observation. Considering the present K-band cryogenic receiver and future Q-band millimeter-wave observation requirements of the Nanshan 25-meter radio telescope at the Xinjiang Astronomical Observatory of the Chinese Academy of Sciences, this paper presents a design of a K-band room temperature receiver. The receiver works at 22-24.2GHz and eventually outputs 3.95-6.15GHz IF signal through mixing. It is mainly used for amplitude calibration method practice and atmospheric opacity measurement in K-band. Finally, the noise temperature of K-band room temperature receiver is 402.2K (theoretical calculation is 410.6K), and the standard noise source is 166.3K. Combining with the mechanical structure of chopper wheel calibration, the K-band receiver has the functions of amplitude calibration and atmospheric opacity measurement, and this work can pre-research on technology for Q-band millimeter-wave observations of Nanshan 25m radio telescope for the future.