Abstract: Because of many advantages of SOI (Silicon-on-Insulator) in comparison with bulk silicon, such as high switching speed, high packing density, radiation hardness, avoidance of latch-up, this technology,as the microelectronics technology in the 21st century, is gaining more and more interest. The SOI technology is now moving into commercial product applications, particularly for high performace and low power CMOS circuits, radiation hardness devices and high temperature electronics. The recent important progress in SOI materials and devices is reviewed.