The European foulbrood disease is one of the common diseases in honey bee breeding all over the world. The main of the bacteria causing this disease is called Melissococcus pluton. The common antibiotics are used to control this disease. Their use in apiaries, and entry into the human body increases the possibility of antibiotic resistance. Therefore, in this research, the antibacterial effects of bee propolis and sepiolite/propolis/silver nanocomposite on Melissococcus pluton bacteria were studied. To carry out this research, first, the required propolis was collected from a number of apiaries in different regions of Kerman province and extracted from them in the laboratory. Then Melissococcus plutonium bacterium was cultured in a special environment and was affected by different dilutions of the extracts. Finally, the MIC and MBC of the samples were determined by disk diffusion and well plate tests. The obtained data were analyzed by SAS software. The results of this research showed that although the alcoholic extracts of propolis and sepiolite/propolis/silver nanocomposite had less antibacterial properties compared to the standard antibiotics used in beekeeping (P<0.01). But they have had a significant effect on the inhibition and lethality of Melissococcus plutonium bacteria. So that propolis and sepiolite/propolis/silver nanocomposite at concentrations of 80 and 90 mg/ml respectively had inhibitory properties and at 200 mg/ml concentration had the ability to kill the desired bacteria. The results showed that honey bee propolis and the nanocomposite obtained from it have antibacterial effect on the agent of European foulbrood diseases in honeybee.