A portable sunscreen applying apparatus and a sunscreen application reminding method are provided, and the portable sunscreen applying apparatus includes: an ultraviolet processing device and a sunscreen accommodating device connected with the ultraviolet processing device, the sunscreen accommodating device is configured for accommodating sunscreens of different protection levels; the ultraviolet processing device includes: an ultraviolet detecting unit, for detecting current ultraviolet and obtaining an intensity of the current ultraviolet; and a sunscreen application reminding unit, for issuing a warning reminder of one of the sunscreens of the protection level corresponding to the intensity of the current ultraviolet. The ultraviolet processing device and the sunscreen accommodating device are provided together, the intensity of the current ultraviolet is detected by the ultraviolet detecting unit in the ultraviolet processing device, and the user is reminded to use the appropriate sunscreen.