The physical mechanism of delayed breakdown diode(DBD) was analyzed. Considering both the amplitude and the rise time of the output pulse across the load, the characteristics of DBD with different structure parameters and physical parameters (length, area, doping and the stimulating source) were simulated. The simulation results show that there exists a minimum value for rise time with respect to both the area of the DBD and the load resistance. The minimum value should be adopted in design. Theoretically the optimum length of n region should be the maximum punching through length. The lengths of p+ region and n+ region have little influence on the DBD performance, which should be greater than their punching through lengths. And their doping density, the higher the better. As regard to the