ABSTRACT In-car smart devices, such as touchscreen control systems, internet interfaces and hands-free phone functions can cause problems affecting driver comfort, visual fatigue and performance, resulting in decreased reaction times, increasing the likelihood of accidents. This study utilizes a touchscreen display and driving simulator as the operational tools in experiments designed to investigate how changes in screen brightness and different color combinations affect the visual performance and the level of visual fatigue of the driver. Specifically, the aim is to explore the impact of changes in brightness and color combinations on visual fatigue and whether there are interactions between them. During the experimental process, relevant data, including the Critical Fusion Frequency (CFF), touchscreen offset, and the NASA Task Load Index (NASA-TLX), are collected and then analyzed using the SPSS statistical software to provide objective and reliable supporting data and valuable insights to related research fields. The experimental results show that the environmental illumination significantly affects the touchscreen offset, CFF and the NASA-TLX), while the color combination significantly affects touchscreen offset (movement and rotation) and the NASA-TLX.