An aroma-diffusing heating device using an aroma capsule is provided, including a hollow housing, a heat conduction unit and a heating element. The heat conduction unit is disposed in the hollow housing. The heating element is disposed on a bottom side of the heat conduction unit. The heat conduction unit has an aroma capsule placed thereon. The hollow housing has a funnel-shaped space formed between a slanting slide portion and the aroma capsule to define an operation space. A user is allowed to grab the protruding edge of the aroma capsule with his fingers and place the aroma capsule in the heat conduction unit, and his fingers can slide through the slanting slide portion into the operation space. Therefore, the fingers can enter into and leave from the operation space easily.