This Paper presents an overview of the development in the filed of polymerase chain reaction (PCR) on-microchip and its applications. It summarizes the different types of PCR microchip designs, fabrication methods, multi-step integration and applications, Problems of evaporation and inhibition PCR that attributes to the surface chemistry of microchip components are also discussed, and the relevant solutions are brought forward. The development of microchip PCR is prospected as well.