High-speed rail (HSR) is advancing at an unprecedented speed in China. However, its impact on the road passenger transport (RPT) is under-investigated. In this paper, a questionnaire survey of RPT and HSR passengers in Shaoguan, Wenzhou, and Shantou, China, was carried out to pursue the sustainable development of RPT and HSR from the aspect of passenger mode choice behavior. The travel mode in the three cities was further investigated using a binary logit model. The findings show that improving the safety and comfort of RPT, as well as the fares and convenience of HSR, are most likely to change passenger choice. For every one unit increase in passenger satisfaction with either the safety or comfort of RPT, the ratio of the probability of passengers choosing RPT to the probability of passengers choosing HSR will increase by 1.6 times and 4.8 times, respectively. Additionally, for every one unit increase in passenger satisfaction with either HSR fares or convenience, the ratio of probability of passengers choosing HSR to the probability of passengers choosing RPT will increase by 4.95 times and 7.011 times, respectively. This study’s results reveal the factors influencing passengers’ choice of HSR and RPT, providing crucial perspectives on sustainable developments for future HSR and RPT projects. Findings from this study may be used by transport planners to provide policy recommendations not just for China, but also for other countries that are building HSR systems.