An external structure of an outdoor electronic apparatus for packaging a circuit board having a power line is provided. The external structure includes a housing having an opening and a waterproof gasket. The waterproof gasket includes a main body, a platform portion, a first protrusion, and a bushing portion. The main body covers the opening. The platform portion, located at the inner side of the main body, extends into the housing from the opening. The platform portion seals the opening and tightly fits with the housing. The first protrusion is located on the platform portion for abutting against the circuit board. The bushing portion, located at the outer side of the main body, has a channel. The channel passes through the main body and the platform portion and can be passed through by the power line. The bushing portion and the power line tightly fit to each other.