According to the reaction mechanism in non-chain pulsed DF lasers, a dynamical model for this kind of laser is presented by using rate equations theory. The optimum gas ratio and reflectance of output mirror are obtained by numerical calculation with this model using the Runge-Kutta method. The experiment is done based on UV-preionized discharge method. The main output parameters of non-chain pulsed DF laser gained from experiment agree well with the theoretical calculation. The theoretical analysis and experimental results both show that the output performance of non-chain pulsed DF laser can be improved by optimizing the parameters of working gas pressure ratio and the reflectance of output mirror. The laser has the best output performance when the working gas ratio is 101 and the reflectance of output mirror is 30%. The single pulse energy of 4.95 J, pulse duration of 148.8 ns and peak power of 33.27 MW are achieved under above conditions.