Based on the reaction mechanism of non-chain pulsed DF laser and taking into consideration the deactivation of the stimulated DF molecules by ground state DF molecules, D2 molecules, D atoms, F atoms, the dynamical model for non-chain pulsed DF laser is established using the rate equation theory. Through solving this model with Runge-Kutta method, the dependence of species concentration in the gain area on time is obtained. Then the effects of the working gas ratio and the reflectance of output mirror on photon number density, single pulse energy, pulse width and output power are studied in light of this model. The optimum parameters of the working gas ratio and the reflectance of output mirror are attained based on the theoretical calculation. The pulse waveform and single pulse energy of non-chain pulsed DF laser calculated by using the rate equations theory agree well with experimental data based on electric-discharge. These results would provide a theoretical support for the optimization of non-chain pulsed DF laser.