The present invention provides an omnidirectional antenna and an electronic device. The omnidirectional antenna includes a dielectric substrate, a first metal sheet and a second metal sheet that are printed on a surface of the dielectric substrate, wherein the first metal sheet is rectangular, the second metal sheet is in a strip shape with one wide end and one narrow end, the first metal sheet and the second metal sheet are arranged in a coaxial manner and spaced one another, and the wide end of the second metal sheet is close to the first metal sheet.