Recent years,much attention has been paid on Terahertz and a fast development on terahertz science and technology has been achieved. However,there is much difficulty to fabricate terahertz devices with classical electromagnetic microwave technology or optical means based on quantum mechanics. In the later nineties,with the improvement of manufacture method on photonic crystal in terahertz band gap,terahertz devices based on photonic crystal emerged. Therefore,an overview on photonic crystal terahertz devices,such as photonic crystal Terahertz filter,photonic crystal Terahertz waveguide,photonic crystal Terahertz fiber and photonic crystal Terahertz cavity is presented and analyzed,and some suggestible perspectives are also given in the end.