Abstract: It was found that influence of distance between label card and card reader on reading card efficiency of EPC Gen2 system is big in application of EPC Gen2 system: signal that some label cards fedback to card reader became too weaker to be identified with increasing of the distance; the signal sent by some label cards with weak reflection signal were more difficult to reach card reader with increasing of the distance when needing simultaneously identify many label cards. Quantized experiments were made for the above problems and got following result: it did not appear situation that label cards were missed reading when distance between label cards and card reader was 3 m and the reading time was short; it appeared situation that some label cards did not be read in 2 min when distance between label cards and card reader was 5 m. The experiment result showed that reading card rate and read rate of EPC Gen2 system decrease obviously with increasing of distance between label cards and card reader, EPC Gen2 system is not suitable for application of long distance and simultaneous identification with higher reliability.