The Caltech Submillimeter Observatory (CSO) telescope will be moved from Mauna Kea, Hawaii, to Chajnantor Plateau, Chile, in 2023, refurbished there and renamed as Leighton Chajnantor Telescope (LCT). LCT’s servo control system plays an important role in realizing the high pointing accuracy (1 arcsec) for submillimeter astronomical observations. Based on the hardware-in-the-loop (HIL) simulation technology, this paper proposes a real-time simulation platform for the LCT’s servo control system, in which the Speedgoat target machine, the SimuCAT communication interface, the ARM-based controller, and MATLAB/Simulink-based simulation model are integrated seamlessly. Based on the real-time simulation platform, the servo control algorithm of LCT is implemented and its performance is evaluated.