This article introduces a design principle and implementation method of a high-speed digitizer based on PXI bus technology.It describes the system composition from two sides of the hardware and software.The acquisition platform is based on ultra high-speed ADC-ADC08D1500 and high performance FPGA-VIRTEX-4 SX35,and it can realize the 3Gsps real-time sample rate and 8 bit sample accuracy.The on-board DDR2 dram module can realize high-speed data real-time storage.The PCI9054 is used as interface IC for PXI bus.The DLL API mode is used in software development.That is convenient for different user's customizing.