Abstract: Algorithms for the flow field of detonation products behind 2D curved detonation waves are given. Detonation propagation is described by detonation shock dynamics, and detonation front positions are computed by the LS methods. Detonation propagation and coupling between the detonation front and the flow field of detonation products behind the detonation front are calculated by a program burn method, in which the reaction process variable is defined by the LS functions. Calculated results for 2D detonation wave diffraction from a rigid finer tube to a coarser tube show that chemical reaction rates do not influence the flow field distribution behind the detonation front, only affects the reaction zone structure. The proposed method can deal with the driven problems of insensitive explosives.