Using data observed by two GPS ionospheric scintillation monitors located near each other at Guangzhou station, the amplitude scintillation was measured, and the zonal drift velocity of the ionospheric irregularities was studied by choosing three scintillation events, with methods of signal intensity power spectrum and cross-correlation technology. The results show that each of the scintillation registered in two receiver monitors occurs at the same time and induced by the same ionospheric irregularity. The zonal drift velocity is about 50m/s to 160m/s, on average about 120m/s from the two calculating methods, varies significantly at the beginning of the scintillation, decreased with time and eastward. The characteristics of the zonal drift velocity in Guangzhou are consistent with the observation at other stations in the low latitude region, which indicate that the two calculating methods are feasible and effective.