The communication system which was the point of large ground-based telescope was presented, for meeting partial systems′ large number, data classes′ variety, data transmitting long distance and data′s uneven distribution. The system was made up by up data communication system and the bottom one. By using FPGA, the maximal communication capability of system was promoted to transmit 60 paths of RS422, 32 paths of TLL, 10 paths of RS485 and 4 paths of RS232 in one time, while the connection between up and bottom system was single optical fiber. In addition, the telescope′s working clock was supported by GPS, and the real-time spatial and time information was given by catching exposure signal′s time and encoder data. The XILINX′s Virtex-5 FPGA was designed in the heart place. The experiment results indicate that the system is valuable for large ground-based telescope.