The invention discloses a patch antenna with a high cross polarization ratio and a communication base station. The patch antenna comprises a substrate, a metal reflecting surface, a main radiating surface and a parasitic radiating surface, wherein the main radiating surface is arranged on the upper surface of the substrate, and is provided with a main radiating sheet and a feed port, a convex structure is arranged at one end of the main radiating surface, the convex structure is an inverted T shape, the convex direction of the convex structure is the direction of the feed port and is parallel to the feed port, the two sides of the convex structure are connected with the feed port, the metal reflecting surface is positioned on the lower surface of the substrate and is integrally formed through a laser etching or selective electroplating technology, the parasitic radiating surface comprises a parasitic radiation sheet arranged right above the main radiation sheet in parallel, and the parasitic radiation sheet is fixed on the substrate through a support column. By adopting the structure, the convex structure is arranged on the main radiation sheet to improve the polarization purity of the main radiating surface, so that the cross polarization ratio of the patch antenna is further improved; and the structure adopts two-point feed, so that the patch antenna is simple in wiring.