Abstract: The MEMS capacitance diaphragm gauge （CDG）, a miniaturized alternative to traditional mechanical vacuum gauges, offers key advantages for applications in microelectronics, aerospace, and deep space exploration, including compact size, high precision, and gas-independent operation in medium-to-low vacuum environments. However, its performance is highly susceptible to environmental temperature variations. A thorough understanding of its temperature characteristics is therefore critical for implementing effective temperature drift compensation and enhancing measurement accuracy. This study investigates the temperature-dependent behavior of a MEMS CDG developed by the authors. Based on the device's structure and operating principles, two primary mechanisms are identified as sources of temperature-induced measurement error: （1） thermal expansion mismatch between the silicon diaphragm and the glass encapsulation, and （2） temperature-driven changes in the sealed cavity's reference pressure. Theoretical analyses reveal that the mismatch in coefficients of thermal expansion （CTE） between silicon （used for the diaphragm） and glass （used for bonding and encapsulation） causes structural bending as temperature rises. This bending reduces the electrode gap, thereby increasing capacitance. Concurrently, the reference pressure in the sealed cavity increases with temperature, causing slight diaphragm deflection toward the fixed electrode and further modifying capacitance. Experimental evaluation over a temperature range of −20 ℃ to 50 ℃ and a pressure range from 0.1 Pa to atmospheric pressure confirms these effects. At zero pressure, output capacitance increases linearly with temperature, while across the full temperature range, the capacitance-temperature response exhibits nonlinear behavior. A maximum relative deviation of 3.1% in output capacitance was observed for a 10 ℃ temperature change. Notably, the temperature-induced error is pressure-dependent, with deviations amplifying or diminishing based on the measured pressure. These findings establish a foundation for implementing robust temperature compensation in MEMS CDGs.