To investigate the detonation characteristics of an insensitive Plastic bonded explosive (PBX), the reaction rate was obtained and used in the numerical simulation of diverse case problems in the one-dimensional and two dimensional space. To calibrate the reaction rate, Detonation shock dynamics (DSD) theory was adopted, and two-dimensional steady-state experimental data were used to determine the shock front curvature function Dn(κ). The reaction rate was calibrated by numerically integrating the master equation of the DSD theory. For the calibrated reaction rate, the simulation of the Large scale gap test (LSGT) and EIDS CAP test with regard to the shock sensitivity problem were carried out. Two numerical example were investigated using the reaction rate. First, an underwater explosion, which is basically a one-dimensional problem, was solved. Second, to also validate the reaction rate detonation wave progress, a corner turning problem was solved. Considering the results of the simulations and the experimental test, it was concluded that the calibrated reaction rate well describes the detonation characteristics of insensitive PBX with a reasonable degree of accuracy. The present study is the first case to obtain the reaction rate of an insensitive castable PBX using the DSD theory. Moreover the reaction rate obtained was verified using different detonation tests such as the gap sensitivity test, the underwater explosion test and the detonation wave propagation test.