The paper deals with the design optimization of SiGe heterojunction bipolar transistor (HBT) on thin film silicon-on-insulator (SOI). The basic DC and AC current characteristics are obtained and the differences between the SOI and bulk SiGe HBT are analyzed. As the incorporation of SOI substrate makes the SOI SiGe HBT a four-terminal device, the influences of the substrate bias on Gummel plot, output current and avalanche current are studied emphatically. Finally, the physical parameters of material and geometric parameters of the device are discussed by changing the frequency characteristics. Compared with the bulk counterpart, the SOI SiGe HBT is designed and fabricated with a great degree of freedom for better performance. This systematic analysis of SOI SiGe HBT provides a valuable reference for the SOI SiGe BiCMOS circuit design and simulation.