In order to investigate the shock initiation of missile warhead (cylindrical covered charge) by multiple fragments impact under actual combat conditions, based on Jacobs-Roslund formula of single fragment initiation plane covered charge, the engineering calculation model of the impact critical initiation condition of cylindrical covered charge with single or double spherical fragments were established. The calculation model includes several parameters, such as fragment diameter, impact angle, charge radius and shell thickness. The calculation model results were in good agreement with the simulation results and experimental results, which proves that the calculation model can provide a better prediction of the impact critical initiation condition of cylindrical covered charge with single or double spherical fragments.