The breakdown mechanism of power bipolar static induction transistor (BSIT) with buried gate structure is analyzed in depth.A power BSIT sample with high voltage-resistant capability has been designed and fabricated in this paper.The technological methods for improving high voltage performances are represented.The active region of BSIT is surrounded with a deep trench to avoid any probable influences of various defects on device performances.Two field-limiting ring-shape junctions and one channel termination ring-shape junction are arranged around the gate region to reduce the electric field intensity.The gate-source breakdown voltage BVGs of power BSIT has been increased to 110 V from previous value of 50-60 V,and its blocking voltage is increased to 1700 V.The optimal geometrical dimensions for achieving the maximum breakdown voltage BVGs and blocking voltage Vblock are also represented in the paper.