This paper reviews several suitable microvalves for polymerase chain reaction (PCR). First, three type micro-valves in PCR chips are discussed, including pneumatic, servomotor-controlled and passive plug microvalves. Then we present our servomotor-controlled microvalves, with the structure of long passive plug. This valve had many obvious advantages such as simple fabrication and operation, perfect sealing, the ability to withstand relatively high pressure. Furthermore, the microvalve can be operated in a self-actuated mode.