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The performance of SOI SiGe HBT structure was enhanced by introducing a buried oxide layer and Si 1-y Ge y collector. Both the base region and the emitter region are subjected to the action of stress, so the characteristic frequency and the current gain are improved. The effects of different step type distributions of Ge mole fraction in the Si 1-x Ge x base and different Ge fraction contents in the Si 1-y Ge y collector on the frequency, the Early voltage, and the current gain are analyzed by employing SILVACO TCAD tools. The results show that the current gain and frequency characteristics of the device can be improved by introducing biaxial stress in the Si 1-x Ge x base region. The step type distribution of Ge components in the Si 1- x Ge x base region can improve the Early voltage. The best performance is achieved when Ge component $y$ is 15% in the collector region. The best current gain is 2386, the Early voltage is 170V, and the cut-off frequency is 240GHz.