Abstract: The U.S. climate reference network (USCRN) is a systematic and sustained network of climate monitoring stations with sites across the conterminous U.S., Alaska, and Hawaii. It is managed and maintained by the National Ocean and Atmospheric Administration (NOAA). The vision of this program is to provide a continuous series of climate observations with the minimum unexplained diversification for monitoring trends in the nation’s climate and supporting climate-impact research. Currently, there are 137 sites in the network, including 114 sites within the continental U.S., 21 sites in Alaska, and 2 sites in Hawaii. These stations use high-quality instruments to measure temperature, precipitation, wind speed, soil conditions, and so on. To avoid further homogeneity or urban impact test and calibration, strict criteria are applied for site selection to ensure the pristine quality of observatory environments in the future. Base on USCRN, NOAA began to deploy U.S. regional climate reference network(USRCRN) across the 9 NOAA climate regions with the same criteria since 2009 to monitor regional climate variation signal. In general, the USCRN could be taken as a benchmark for national climate observational system construction.