In laser ranging, the very weak echo wave detecting is very important and difficult. In order to improve the aim distance and measuring accuracy, the classic method by using the analog electronic technology completely can’t fit for some application any more. Then, a digital high speed data capture system to detect the echo wave was designed which adopted high speed AD unit and FPGA circuit as core devices. At last, the realized system reached 1GHz sampling rate and experimental results showed that it could measure a longer effective aim distance and improve the measuring accuracy highly.