Abstract: The application of perforating completion technology in oil and gas field development has gained widespread popularity. Enhancing the efficiency of oil and gas wells relies on increasing the penetration depth, which is influenced by the design of the perforation charge and the strength characteristics of the rock material. However, as a crucial objective function for optimizing perforating charge structures, jet velocity lacks a rapid and accurate calculating method. This article addresses this issue by proposing an improved collapse velocity model using the DP46RDX42-Y perforating charge as a case study. It presents a novel approach for calculating jet velocity based on the unsteady Pugh-Eichelberger-Rostoker (PER) theory. To validate the effectiveness of the proposed method and analyze the impact of different characteristic parameters on jet tip velocity, a series of numerical simulations were conducted using LS-DYNA software combined with Arbitrary Lagrange-Euler (ALE) techniques. Results indicate excellent agreement between the proposed method and the numerical results, demonstrating its superiority over the traditional Gurney formula with an impressive 34.15% increase in accuracy. Notably, this method is particularly suitable for perforating charges with low detonation velocity. Increasing the liner density and decreasing the liner thickness and cone angle is recommended to achieve higher jet tip velocity. Furthermore, the proposed method has the potential for broader application in other perforating charges with varying liner shapes. This study provides a comprehensive and efficient solution for calculating jet velocity, which facilitates optimizing perforating charge structures and calculating penetration depth.