The continuous medium mathematical modeling of two-dimensional unsteady transonic two-phase reactive flow of explosive particles in high-loading beds is investigated. The SIMPLE method is successfully utilized for two-dimensional numerical calculation of the Defagration-to-Degonation Transition (DDT) processes in high-loading explosive beds. Special treatment for transonic flow and derivation of pressure correction equation for compressible fluid are presented. As an example, the calculated results for non-primary-explosive detonator show that this method weakens the numerical oscillation of transonic 2D-two-phase flow more effectively.