The accuracy of time measurement units ( TMU) in integrated circuit automatic test equipment ( ATE) is facing higher demands due to the rapid development of integrated circuits. To cope with the increased accuracy of digital IC time parameter measurements, a high precision time measuring unit was designed in this paper, which used the electronic pin test chip MAX9979 to apply excitation and capture response, and combined with Xilinx Artix-7 FPGA internal curing time digital converter (TDC). Time-todigital converter implemented by interpolation using a combination of coarse and fine counting, the coarse counter is implemented by a 32-bit direct counter with a reference clock of 200 MHz, while the fine counter consists of a delay chain cascaded by a CARRY4 cascade, with a dedicated configuration for CARRY4 to reduce the measurement error caused by its overrun function, and the delay chain was calibrated using the code density calibration method. The experimental results show that the TMU range is 21. 475 s, the average resolution is 34. 7 ps, the DNL is less than 2. 5 LSB, the INL is better than 4. 5 LSB, and the accuracy is 39. 7 ps.