The invention discloses a horizontal omnidirectional planar printed antenna which is characterized in that the planar printed antenna comprises three metal layers and two medium layers; the upper metal layer and the lower metal layer are metal stratums (1,3); the middle metal layer is a feeding layer (2); the center of the feeding layer is printed with a metal conduction band (5); the metal conduction band, the upper metal stratum and the lower metal stratum form a stripline transmission line; the upper and the lower metal stratums (1,3) are symmetrically manufactured with a plurality of rectangular rifts (6) along the direction of the metal conduction band; and a medium layer (4) is arranged between the metal stratums (1,3) and the feeding layer (2) respectively. The horizontal omnidirectional planar printed antenna has the advantages of high gain, good horizontal omnidirectional property, simple manufacture and low cost.