This paper presents a new Chinese Train Control System (CTCS), the CTCS-2I, for trains traveling up to 350 km/h. Building on the capabilities of CTCS-2, the CTCS-2I system provides safety control for trains traveling at 350 km/h by increasing track-circuit information capacity, changing block section parameters, and adjusting other crucial settings. It solves some key issues of the CTCS-2I system operating on 300 to 350 km/h trains, including train-operation control information content and safe train-tracking intervals. The CTCS-2I offers a train-control system in addition to the European train-control system, ETCS-1; and CTCS-3, which both provide safety control for trains traveling at 350 km/h. Furthermore, the CTCS-2I overcomes the shortcomings of real time in the point-type ETCS-1 and averts complications in CTCS-3, including poor compatibility between CTCS-3 and CTCS-2, as well as the structural overcomplexity of CTCS-3 caused by incompatibility transmission in the track circuit and Global System for Mobile Communications–Railway (GSM-R). By contrast, the CTCS-2I system is characterized by its simple structure, good compatibility, low cost, and easy implementation. The necessity of creating a new kind of train-control system, CTCS-2I, has been proved through analysis of the potential problems found in both the CTCS-3 and CTCS-2. The components and working principles of CTCS-2I are detailed in this paper. The key control techniques for 300 to 350 km/h trains, such as information content, block section settings, compatibility, reliability, and safety, are also described. The performance and characteristics of the CTCS-2I are further compared with CTCS-2, ETCS-1, and CTCS-3.