AbstractTo investigate the formation mechanism of linear hypercumulation (LH) for plane‐symmetric π‐type linear shaped charges (π‐LSC), the formation process of LH was studied by using classical steady jet theory and explosive dynamics. Three associated stages during LH formation were analysed theoretically, including the action of detonation wave and stress wave on primary and additional liners, and two collapse processes of the primary liner. Considering the effect of transmitted stress wave in the additional liner, we proposed a new calculation method for the peak velocity of LH. To verify the theoretical results, a plane‐symmetric π‐LSC along with a classical linear shaped charge (CLSC) known as V‐type structure was simulated by AUTODYN. Results demonstrate that the variation characteristics of the pressure and velocity of LH correspond well to the above three‐stage analysis. The pressure acting on the primary liner is enhanced due to the additional liner, and the truncated structure of the primary liner brings a more reasonable velocity gradient to the spiculate head of LH, evidently improving the peak velocity of LH compared with the CLSC jet by about 70 %. Finally, the penetration experimental results show that the penetration depth by the LH of π‐LSC is greatly improved,73.7 % higher than that of CLSC jet.