Radio Frequency Identification is a kind of non-contact auto-identification technique when many electronic tags transmit their only tag identification code to the reader; there will be collision arising, thereby, the research on collision avoidance is necessary and urgent. With the purpose of decreasing the recognition delay, a Pre-Query Tree Algorithm is proposed through the way of decreasing the collision identification and idle time. In this algorithm, the Binary Query Tree Algorithm is replaced by the Quaternary Query Tree Algorithm to reduce the collision. Meanwhile the slotted Pre-Detection Signal Mechanism is used to eliminate the entire idle time. Combined with the Binary Query Tree Algorithm and the slotted Pre-Detection Signal Mechanism, the collision problem of Radio Frequency Identification (RFID) at the aspect of electronic tag identification is promoted and the number of unnecessary query command is reduced. The simulation results show that Pre-Query Tree Algorithm could reduce the collision, and the entire efficiency of FRID system is improved.