Abstract: At present, in the field of millisecond blasting of geotechnical engineering, it is generally considered that delay time within 3 ms has little effect on blasting vibration of practical engineering, and researches on this aspect are not thorough enough.With the help of numerical simulation and engineering test, this paper studies the effect of 1 ms delay time of between-holes millisecond time have on blasting vibration.This paper uses the principle of free surface formation to calculate the between-holes millisecond time, and on this basis, seven kinds of delay schemes of between-holes millisecond are selected for numerical simulation and they are 9 ms, 10 ms, 11 ms, 12 ms, 13 ms, 14 ms, 15 ms.The optimal millisecond time is determined by blasting vibration velocity, then, the blasting vibration effect of the optimal millisecond time is verified by engineering test.The results of numerical simulation and engineering test show that the variation of blasting vibration velocity caused by the errors of 1 ms and 2 ms is up to 0.9%-8.1% and 2%-13% respectively.Correcting the between-holes millisecond time to 1 ms has an obvious effect on blasting vibration reduction.The between-holes millisecond time of 15 ms has the minimal blasting vibration and the least effect on surrounding buildings, and the vibration velocity of the monitoring point meets safety requirements.