A large-area concrete site was prepared to eliminate the boundary effects to investigate the propagation law of detonation-induced cracks in differential blasting under varying hole spacing. Multiple sets of linear three-hole and cross-five-hole model tests were conducted using electronic detonators and detonating cords as the blasting sources. The propagation length, direction, and crack arrest position of detonation cracks were recorded under different blasting parameters. The key factors affecting crack propagation were identified by combining the experimental results with the theory of sequential controlled blasting. The results indicate that in the three-hole model, a through-crack forms between the blast holes when the middle hole detonates first, followed by the two side holes. However, as the hole distance increases, the crack becomes increasingly irregular. When the distance reaches 25 times the hole diameter, the crack fails to penetrate and no longer propagates along the direction of the blast holes. In the cross five-hole model, a through-crack can only form when the spacing is within 20 times the hole diameter. The crack generated by the first blast tends to propagate towards the nearest subsequent hole. Still, it does not follow a straight path, exhibiting deflection due to the influence of the additional holes. Therefore, to achieve straight cracks along the contour surface in practical engineering, it is crucial to adjust the timing and control blasting parameters based on specific hydrogeological conditions to fully utilize the void effect and the detonation timing difference.