Abstract: With the full use of electronic detonators in open-pit mine bench blasting,the millisecond blasting technology has been further developed. How to improve the interaction force between blast holes by adjusting the delay between holes has become the focus of mine blasting technology research. Based on the concrete model to simulate the millisecond blasting in open-pit mines,a high-speed photography technology and digital image correlation (DIC) test system were established. Based on the full-field micro-strain,high-speed photography technology and numerical simulation,the development process of cracks between blast holes under different inter-hole delay conditions was studied. The results show that the strain duration near the surface crack of the model under explosion load is about 3 ms. When the delay between holes is 3 ms,the next hole initiation can improve the interaction force between holes. The pressure distribution characteristics of the measuring points are shown by numerical simulation. The pressure of the measuring points is the largest when the inter-hole delay is 3 ms,which verifies the accuracy of the model test. Using MATLAB to analyze the numerical simulation results,it is found that the degree of fragmentation is the best when the delay time between holes is 3 ms,which is in good agreement with the model test results. The use of high-speed photography technology combined with digital DIC method provides a new idea for studying the interaction force and crack propagation between blast holes.