The accident happened last night when the wedding car slipped into the Sikouzi Reservoir of Haiyuan County in Ningxia Hui Autonomous Region, killing the driver, the bride and her grandmother.
Two other passengers were rescued from the 20-metre-deep reservoir by local people, according to a police official.
Initial investigation attributed the accident to an icy road caused by two days of snow.
Snow started to fall in regions including Ningxia, Shaanxi, Shanxi, Hebei and Henan since Tuesday, according to the National Meteorological Centre, state-run Xinhua news agency reported.