Abstract: This paper presented a UHF RFID tag antenna used in container and analyzed the effect of the distance between antenna and metal plates and size of metal planes on antenna parameters in detail. It is demonstrated that by selecting the distance between antenna and metal planes and considering real environment properly, detection distance can meet requirement, and gain of the antenna will be enhanced as increase the size of metal plane, however there is a little effect on match of antenna. Therefore, the antenna is suitable for application as container RFID tag antenna.