A dual-band circularly polarized patch array using a sequential-phase feeding network was presented. The array includes four metal patches and a metal square ring. Each rectangle patch was cut in diagonal corners, and was excited by feeding lines on the edge. The feeding lines are microstrip which are connected to the middle metal square ring. In addition, four patches are rotated arrangement. The middle mental square ring is not only a feeding network which provides increasing phase for circularly polarization, but also a radiator which enhances the performance of the array. With this feeding way, the patch array just has single-layer substrate and it is compact. In addition, it radiates circularly polarized patterns in two working bands. Through fabrication, test and measurement, the -10 dB impedance bandwidth of the patch array is 5.17 GHz～5.59 GHz and 5.99 GHz～6.27 GHz. The measured 3 dB AR bandwidth is 5.19 GHz～5.49 GHz and 6.1 GHz～6.18 GHz. 