High explosives (HE) with desirable safety and detonation performances are widely used in weapon system and aerospace engineering. Multipoint initiation is utilized to initiate TATB and thus create overdriven state. High-pressure areas of colliding shock waves are observed by measuring steel dent value and the whole processes, involving multiple wave interactions and overdriven detonation formation, are reproduced using LS-DYNA3D program. Results indicate that the quadruple point is at the center where four shock waves collide, and the double point is between two initiation points where two shock waves collide. When the height of donor explosive exceeds 5 mm, the retardation time of the quadruple point compared to the double point and the individual point are 180 ns and 260 ns, respectively. In addition, overdriven state may disappear when the height of UF-TATB exceeds 9 mm, and the delay effect is negligible for initiating PBX-9502 when the simultaneity of slapper detonators is within 100 ns.