本文将FPGA的快速性和计算机的灵活性通过USB2．0总线有机地结合起来，设计了一个基于FPGA的可调参数FIR滤波系统。此系统由计算机根据各种滤波器指标计算出滤波参数，通过USB2．0对FPGA芯片内部的FIR多阶滤波器进行参数配置，实现数字滤波器参数可调；配置后的FPGA滤波单元完成对A／D采集的信号进行滤波运算，滤波后的数据经过缓存后通过USB2．0总线传输至计算机进行显示、分析和储存等进一步处理。在系统中采用有限状态机对FPGA参数配置模式和滤波模式进行切换，保证了系统的有序运行。-In this dissertation，a reconfigurable FIR filter system based on FPGA is designed，which combine high—speed operation of FPGA and flexibility of computer using USB2．0 interface．According to the filter specialties，the filter coefficients are calculated by the computer．And the configured coefficients of the multistage FIR filter are downloaded to the chip．The filtering computing is completed by the FPGA．The filtered data iS transmitted to the computer through the USB2．0 interface for further processing，such as displaying，analyzing and storing．The states conversion between coefficients configuring mode and filtering mode is finished by FSM(Finite State Machine)，which ensures the system to work orderly．