Abstract: A newstructure of SiGe HBT based on the high resistivity（1000Ω.cm） Si substrate waspresented.The influence of the substrate on high frequency performances was analyzed basing on the parasitic element equivalent circuit model,the material structure and fabrication procedure of the device were designed.The device was fabricated by the buried metal self-aligned technique in a 3μm manufacture process line.The test results indicate that the DC gain is 120,BVCEOis 9.0V,the f_T up to 10.2GHz and f_max achieve 5.3GHz.Compared to the conventional N+substrate,the f_T and f_max of SiGe HBT based on the high resistivity substrate have increased 3.9GHz and 1.5GHz respectively.