Xihe, also known as the Chinese Hα Solar Explorer (CHASE), is designed to test a newly developed satellite platform and conduct solar observations. The scientific payload of the satellite is an Hα imaging spectrograph (HIS), which can, for the first time, acquire full-disk spectroscopic solar observations in the Hα waveband. It will complement the observations by on-orbit solar spacecraft (such as SDO, IRIS, STEREO and PSP), as well as future solar missions of the Solar Orbiter and the Chinese Advanced Space-based Solar Observatory (ASO-S). Mission is named Xihe after a solar deity from Chinese mythology.