Abstract: Huaihe River Basin is a transition zone of climate between the northern and southern of China, where meteorological disasters occur frequently. Water networks, farmlands, hills, mountains and towns are densely distributed in this region with complicated air-land interactions. The convergence of cold dry air and warm moist air occurs frequently, resulting in local or basin-scale disasters. The Huaihe River Basin is located in Meiyu area and is an important agricultural production base in China. There are comprehensive meteorological and hydrological observation systems in this region, and long-term meteorological and hydrological observational data have been obtained. Therefore, the Huaihe River Basin is an ideal experiment area for the study of water and energy cycles. The project "HUaihe river Basin energy and water cycle EXperiment (HUBEX)", which was sponsored by the National Natural Science Foundation of China, carried out a joint observation experiment of meteorology and hydrology in the Huaihe River Basin in the summers of 1998 and 1999. The present paper reviews the purpose of the HUBEX, the design and layout of the observation network, and introduces the development of observation network in the Huaihe River Basin based on HUBEX. The achievements and functions of the HUBEX are summarized from the perspectives of the mechanism study of regional climate events and rainstorms, the improvement of the model ability for simulation and prediction, and the establishment of long-term continuous meteorological observation dataset, etc.