Time to digital converter (TDC) is a kind of instrument which can identify the time of events and convert analog signals into digital signals. It is widely used in scientific research fields such as statistics of laser pulse distribution, particle collision time, quantum optics, quantum key distribution, optical detection and lidar ranging. TDC100 is a compact and easy-to-expandable PCIe board-card TDC. It supports three modes of channel difference measurement (start channel can be selected arbitrarily), pulse width measurement and pulse spacing measurement. It has the function of pulse auxiliary count in each channel, and has the characteristics of ultra-high resolution, multi-channel output and high data conversion rate.