Since the general nonlinear explicit dynamics software does not have a mathematical model suitable for simulating the action process of pyrotechnic actuated devices, the dynamics simulation can only be performed by multi-software co-simulation. In order to simplify the simulation process, the pressure-time history (p-t curves) of the pyrotechnic composition under constant volume conditions was simulated using the newly embedded deflagration equation of state of MSC.Dytran software. Simulation of slow-burning carbon black/potassium nitrate and fast-burning aluminum/potassium perchlorate were carried out and compared with experimental results to verify the applicability and accuracy of the simulation method. The time differences when the pressure rises to half of the peak pressure (0.5p_m) and reaches the peak pressure (p_m), and the relative errors of p_m were compared and analyzed between the simulation results and the closed bomb test results . Results show that when the pressure of charcoal/potassium rises to 0.5p_m, the time difference between the simulation result and the test result is 0.03 ms, the time difference when reaching p_m is 0.3 ms, and the relative error of p_m is 10%. Correspondingly, the time difference of aluminum/potassium perchlorate at these two conditions is 0.02ms and 0.1ms, and the relative error of p_m is 4%. The p-t curves simulation of pyrotechnic compositions using the deflagration equation of state in MSC.Dytran software has good accuracy and applicability.