Molybdenum disulfide (MoS 2) demonstrates remarkable capabilities in maintaining low friction coefficients under vacuum conditions. However, its porous structure results in low hardness and poor thermal stability, which limit their load-bearing capacity and self-lubricating performance in high-temperature vacuum applications. Element doping is one of the promising strategies to address these issues in MoS 2 films. Here, MoS 2/a-C:Si composite films with varying C and Si contents were deposited by adjusting the direct current supplied to the graphite-silicon (C-Si) mosaic target. A systematic investigation was conducted to elucidate how the co-doped C and Si influenced the microstructure and mechanical properties of the films. Furthermore, over a wide range of temperatures from 25 °C to 400 °C, the tribological performance of the films was evaluated under vacuum conditions. Results demonstrated that C and Si doping significantly enhanced the density of MoS 2 film. It also inhibited the crystallization of MoS 2 films, promoting the transition from a crystalline to an amorphous structure. Meanwhile, C and Si doping greatly improved the hardness, adhesion strength and compressive stress of the films. In addition, friction test results revealed that MoS 2/a-C:Si composite films containing optimized C and Si contents (sample S2, S3 and S4) exhibited remarkable tribological properties under vacuum conditions across a broad temperature range (25 ∼400 °C), achieving ultralow friction coefficients of 0.04–0.06 and wear rates on the order of ∼10 −6 mm 3/(N·m). The self-lubricating mechanism of MoS 2/a-C:Si films was revealed by analyzing wear tracks and wear debris after vacuum friction tests at various temperatures. During the friction process, under the combined effects of the tribochemical induction of MoS 2 and the induction of contact stress, the composite film formed lamellar graphite with low shear force and (002)-oriented MoS 2 with excellent lubricating properties, resulting in low friction coefficients and wear rates. In summary, this study demonstrates that optimal C and Si co-doping (e.g., samples S2-S4) enables MoS 2/a-C:Si composite films to achieve excellent self-lubricating and anti-wear performance in vacuum across 25–400 °C. The findings provide both an experimental basis and theoretical guidance for designing self-lubricating, anti-wear MoS 2 films suitable for high-temperature vacuum environments.