To ensure reliable services for high-speed freight rail transport, we address the issue of robust freight train timetabling by incorporating buffer times. Unlike passenger trains with prescribed timetables, high-speed freight train timetables need to be scheduled from the beginning and integrated into existing passenger schedules. To achieve reliable high-speed rail freight services, we introduce robust parameters that determine the buffer times for train operations and station stops. Using these, we develop an integer linear robust model aimed at maximizing timetable robustness, considering given control parameters, while minimizing travel and deviation times. We employ an integer Benders decomposition algorithm to solve this model efficiently. Our robust optimization method is validated through experiments using data from the Chengdu-Chongqing high-speed railway, demonstrating the efficacy and efficiency of our model and algorithm, especially in balancing efficiency and robustness.