The invention relates to a digital correlator. The digital correlator comprises a sampling module, a multiplexing module, a correlation calculation module, a synchronous sampling clock module and a synchronous control module, wherein the sampling module is realized by adopting an analog-digital converter with the sampling rate being equal to or higher than 5GHz; the multiplexing module, the correlation calculation module and the synchronous control module are realized on an FPGA chip with the main frequency being higher than 400MHz; different sampling units in the sampling module are used for carrying out high-speed sampling on external input signals respectively and obtaining two paths of digital signals which are input into the correlation calculation module after being multiplexed by the multiplexing module; the correlation calculation module is used for carrying out speed reduction and correlation calculation on inputted digital signals; the synchronous sampling clock module is used for ensuring consistent phase of sampling clocks reaching the different sampling units in the sampling module, and the synchronous control module is used for controlling synchronous working among the different sampling units in the sampling module.