Dry-type DC capacitors are pivotal elements in power electronic converter devices, serving essential functions in voltage support and filtering. The electrical and temperature resistance properties of the core material, biaxially oriented polypropylene film, directly impact the insulation capabilities of the capacitors. This study selects three types of polypropylene film materials, vapor-deposits them into distinct metallized films, and fabricates elements. It conducts experimental research including terminal withstand voltage, durability, and ultimate withstand voltage tests. Experimental results indicate that the three types of film material elements perform similarly in the terminal withstand voltage and durability tests. However, elements made from HC300BF film material exhibit superior ultimate insulation performance, while those made from GC-2 film material demonstrate effective ultimate insulation at elevated temperatures. This suggests that enhanced isotacticity and temperature resistance of polypropylene film materials significantly influence the ultimate insulation performance of dry DC capacitors.