Bounds of undetected error probability (UEP) for binary constant weight codes (BCWCs) are studied in this paper.Firstly
by using the dual distance distribution and its properties for BCWC
we obtain a new lower bound of UEP for BCWC which improves the best known corresponding results by Fu-Kl ve-Wei.We point out that there are mistakes in results of Fu-Kl ve-Wei in 2003 which discussed the upper bounds
and a new upper bound of UEP for BCWC are obtained.