A laser detection system is divided into three parts, which are laser emission, laser receiving and echo signal processing. Traditional laser range finder is used as laser emission module. Laser receiving tube is used in laser receiving module, signal processing module is realized by field programmable gate array (FPGA) and a high precision time-delay module is used to simulate laser distance. The buffer storage and processing of the sampling data, the clock control, logic control and sequence control of the whole circuit are mainly completed. The laser echo simulation system is used to simulate the transmission process of laser echo in atmosphere and provide remote virtual targets, and to get the longest measurement range parameter. With FPGA series Spartan-6 as the design platform, a 300 M internal frequency multiplier circuit is used in the high speed clock circuit to realize 3 ns time-delay precision. The system has the characteristics of high speed, good real time and FPGA has the characteristic of parallel processing.