After the national examination civil servants are admitted, the minimum service period is five years. In principle, they must serve in this place for five years before they resign. However, during this period, as long as you get the approval of the unit leader, you can participate in the selection of the unit or the examination of other positions. However, generally speaking, you can't resign without reaching the length of service.
For more information about the national examination, please refer to: Sichuan Zhonggong Education-National Civil Service Examination Network.
If in doubt, please consult the public education enterprises in China.