The characteristics of 1 310 nm differential-phase-shift quantum key distribution are discussed,the influence of sequential attacks with intensity modulation on which is also analyzed.It indicates that the 1 310 nm is suitable for high speed quantum key distribution over 10-50 km distance.Sequential attacks with intensity modulation will not change Bob′s detection probability and this behavior can be hided by the inherent error rate,so the decoy states technique can not beat it.Based on the L.J.Ma et al experimental data,we evaluated the security of it,and the result indicates that under the sequential attacks,the upper bound of key generation rate is 6.9 Kb/s at 50 km,so it turns out to be insecure.