In order to detect and separate the information of two Radio Frequency Identification (RFID) collision tags, a detection method based on inherent memory characteristics of FM0 tag coding in Gen2 standard is proposed. By analyzing the characteristics of FM0 bit coding and memorylessly detecting the collided tags information, the conditional error probability of memoryless detection method based on the duration of single bit and the bit error rate of single tag information detection are obtained. Then a pair of measurement results corresponding to the first bit and another pair of measurement results corresponding to the next bit are got by using the characteristic that encoding of a single FM0 bit requires memory of the previous bit. The conditional error probability and bit error rate performance for one bit memory auxiliary detection of collided tags information are obtained thereafter. The performance of total delay time reduction for N tag groups is also analyzed in framed Aloha medium access scheme where the proposed detection method is adopted. The simulation results show that the proposed one bit memory auxiliary detection method has better Bit Error Rate(BER) performance than memoryless detection, and it can also reduce the total delay time of tag group accessing.