Abstract: High-speed amplifier and comparator were adopted to complete waveform amplifying and reshaping. With FPGA as processing core, accurate frequency measurement of input signal can be obtained. 5 measurement scales were divided to support 1 Hz~100 MHz frequency measurement internally. Automatic scale switch was implemented, too. Furthermore, duty measurement of square wave, and time interval analysis of 2 homologous square wave all supported. MCS-51 microcontroller was utilized to complete final result calculation using FPGA’s original measurement data, and these results were displayed via LCD. Corresponding relative measurement error was less than 10^－4. Presented design can be used for low-cost digital frequency meter design.