A-One is a mandopop group created in 2008 under the label Hong Kong Kiss-star entertainment Beijing company
Originally Gillian Chung was scheduled to be a performer at the 2008 Summer Olympics opening ceremony. But due to the Edison Chen photo scandal, director Zhang Yimou had replaced Twins with A-One. A-One did not make their international debut on 8 August as part of the ceremony.
After 2 years of training the group debuted after Hunan Satellite TV show Happy camp (快乐大本营).
The group members are counted as 3+x where the most popular 3 members are in the group. Sometimes it may have 5 or more members. There had been 10 members in total. The official website describe this fan selection style as democratic (民主) for the 21st century.