In this study，a laser-pulse flight-time measurement and data-processing method is designed based on a field-programmable gate array(FPGA)in response to the large-scale，high-precision， highly real-time property and lightweight integration requirements of laser-ranging technology proposed by intelligent unmanned platform. Additionally， the method is devised to address the challenges of complex systems and subpar scalability caused by the dependence of conventional laser-ranging methods on dedicated time-to-digital converters and constant-ratio timing-threshold discrimination circuits. A measurement accuracy of 1 ns is achieved using the high-frequency clock counting of the FPGA and multiphase time interpolation. A pulse-width compensation method is designed to correct the time drift error caused by changes in the laser echo power at different distances. The ranging results of the prototype show that the time accuracy reaches 1 ns and the measuring error is ±0. 15 m within the range of 10 m to 5 km，thus satisfying the requirements of large range and high precision simultaneously.