Three kinds of typical bacteria were selected as the experimental strains, E. coli, K. marina and B. subtilis, in order to study the bactericidal effect of ultrasonic combined with sodium hypochlorite and the lethal kinetics of microorganism. Three common models were selected, namely first-order kinetics, Weibull, and Logistic models, to fit the inactivation curve of three typical strains by ultrasonic combined with sodium hypochlorite. Besides, the damage degree of the morphological structure of the bacteria before and after sterilization and the loss of materials in the cells were measured. The results showed that when the ultrasonic power was 150W, the concentration of NaClO was 200mg/L, and the treatment time was 180s, the lethal dose logarithm to three kinds of bacteria was 4.54,4.28 and 3.97, which was 13%~67% higher than that of sodium hypochlorite alone at the same time. With the increase of ultrasonic intensity and the concentration of sodium hypochlorite, Weibull model was more suitable to describe the sterilization process than logistic model (R2>0.95). At the same time, through the results of scanning electron microscopy and the loss of material in the cell, it was found that the combination of ultrasound and sodium hypochlorite can destroy the outer structure of the cell, make the cytoplasm overflow, the organelle dissolve and the cell shrink, and finally cause the cell death. The research result can provide an important method basis for the combination of ultrasound combined with sodium hypochlorite widely used in microbial sterilization.