RFID　system　is　widely　used　in　wireless　communication　systems.　Tag　collision,　causing　the　RFID　reader　cannot　Identify　the　tag　data,　Is　a　serious　problem　when　several　tags　use　the　same　communication　channel　simultaneously.　Framed　slotted　ALOHA　algorithm　is　normally　used　to　solve　the　RFID　collision　problem.　However,　It　requires　an　exponentially　increasing　number　of　slots　with　the　tags　number　increasing.　An　improved　anti-collision　algorithm　Is　presented　In　this　paper,　which　has　a　lower　collision　probability　and　needs　fewer　slots.　The　proposed　algorithm　has　been　used　In　a　433MHz　RFID　system　and　reduces　the　tag　collision　probability　successfully.