The ultra wide band capability of the thick single pole vibrator antenna is studied with the method of moment (MOM) in this paper. The antenna's current distribution, input impedance, radiation direction patterns, the varying characteristics of voltage standing wave ratio (VSWR) with frequency are studied respectively. The results show that this antenna has a good ultra wide band capability. A thick single pole vibrator antenna, 50mm long and 5mm in diameter, fed with 50Ω coaxial line and with its base connected to an infinite large conductor plate, is designed at frequency f0 = 1.4CH z. The testing results are satisfied with the theoretical ones on the whole. And the ultra wide band capability is proved and verified in practical use.