Abstract: In order to capture 3-D image instantaneously by transmitting single laser pulse of array lidar, solve the problem of multi-channel ranging, a 25-channel concurrent ranging system was developed. A multi-core parallel processor was consisted of four measuring units and one data multiplexing unit. Each measuring units contained 8-channel trans-impedance amplifiers, 8-channel high speed comparators, a TDC-GPX chip, and a STM32 microprocessor. Multi-channel data package and upload were completed by field-programmable gate array(FPGA) in multiplexing unit. Experimental results indicate that range error is less than 25cm. The ranging system has the feature of openness, ranging channel can be increased easily, and circuit boards are interchangeable. Error correction method based on distance is presented. The correction of ranging data can be accessed directly by single laser pulse detection without the repetition of measurement. The study gives the foundation for researching and manufacturing of array lidar with higher precision.