a novel design of patch antenna for 2.45GHz passive RFID tag is proposed. Rogers RO4232 (tm),Rogers RO4003 (tm) and short glass fiber reinforced PTFE are introduced as composite substrate. Ansoft HFSS 10.0 is employed for the building of antenna model. Simulation results match the theory-expectation. Through optimization, the system performance meets the requirements, such as good directivity, effective gain 5.534dB, bandwidth>50MHz(S11<-15dB),well impedance matching. Standingwave ratio and radiation efficiency agree with the prediction. The proposed antenna model well satisfies actual application needs for aeroquip fittings and maintenance record. Meanwhile it is easily realized, cheaper and more reliable.