A wearable electronic device includes a middle frame, two connecting sidewalls, a first metal sidewall, a first dielectric component and a first antenna layout trace circuit. The two connecting sidewalls are disposed at two opposite sides of the middle frame for connecting a wearable component. The first metal sidewall is disposed at the middle frame and located between the two connecting sidewalls. The first metal sidewall is connected to ground and includes a first slot. The first dielectric component is installed in the first slot, so that the first metal sidewall surrounds the first dielectric component to form a first closed ground structure. The first antenna layout trace circuit is installed on the first dielectric component. The first antenna layout trace circuit and the first closed ground structure associate a first resonate frequency.