The technology for high voltage level and three- pedestal width- adjustable fast pulse generation is revealed in this paper. The voltage level can be adjustable from 200 to 700 V, and the width of pedestal can be adjusted within 100 μs . This technology is already applied in the experiments and the experimental results match the expectations. Single longitudinal mode laser powered by this adjustable three- pedestal pulse can be smooth and stable. This technology can be used during the design of high power laser facility and other equipments with multi-pedestal high voltage fast pulse generator.