This paper investigates the sensitivity of the steam outlet temperature in the THTR (High-Temperature Gas-Cooled Reactor) steam generator. The THTR steam generator employs helium as the primary loop medium and water as the secondary loop medium. During actual operation, deviations in the steam outlet temperature have been observed. To identify the causes of these deviations, a thorough analysis is necessary. By examining the impact of various thermohydraulic parameter changes on the outlet steam temperature of the steam generator, the reasons for the temperature deviations can be effectively pinpointed. Based on the design characteristics of the direct-flow steam generator in the HTGR system, a specialized thermohydraulic analysis program has been developed in this study to analyze the sensitivity of the steam outlet temperature. This research provides theoretical support and practical guidance for optimizing the operational parameters of the THTR steam generator, enhancing system stability, and improving efficiency.