Abstract: Dry-type power capacitors generate heat due to dielectric loss during operation, and their heat dissipation performance is greatly affected by the mounting inclination angle. In engineering practice, capacitors are conventionally installed in either a horizontal (lying flat, terminals horizontal) or vertical (upright, terminals vertical) orientation, but a systematic understanding of the temperature distribution under various inclination angles remains insufficient. Aiming at the problem of uneven internal temperature distribution of capacitors under different mounting inclination conditions, this paper establishes a thermal-flow coupling simulation model of dry-type power capacitors that takes the mounting inclination angle into account. The distribution laws of temperature field and flow field under six typical inclination angles of 0°, 15°, 30°, 45°, 60° and 90° are analyzed, revealing how inclination influences natural convection heat transfer coefficient and maximum temperature rise. The simulation match well with experimental data, further confirming the superior heat dissipation of verticol installation compared with horizontal installation, consistent with prevailing engineering practice. Structural optimization schemes incorporating the capacitor’s own geometric dimensions are proposed for various installation angles to reduce hot-spot temperature and enhance operational reliability.