Abstract: In order to understand the influence of the delay time between holes on the rock breaking effect of different rocks, a numerical model of double−hole blasting was established by means of numerical simulation using limestone from a mine as an example, and 34 parameters of the RHT constitutive model of limestone were calibrated. The simulation results showed that the stress enhancement phenomenon increased with the increase of delay time, but when Δt increased to 80 μs, the stress enhancement caused by the superposition between holes can be ignored. The crack propagation area of the pre−blasting hole increased with the increase of the delay time, the crack propagation area of the post−blasting hole decreased with the decrease of the delay time, and the width of the crack propagation between the holes increased with the increase of the delay time. The research results provide a design basis for the popularization and application of the precise delay performance of digital detonators.