Ducks are one of the most popular livestock in Indonesian society. Maintenance of ducks is mostly done extensively, namely grazing in paddy fields or ditches. This method can cause ducks to be susceptible to disease and can spread quickly because ducks are grazed to move places. One of the diseases that attacks ducks is Salmonellosis caused by the Salmonella sp. bacteria. One way to kill Salmonella sp. bacteria is by using ultraviolet (UV) light. The purpose of this study was to find the right UV irradiation method to weaken the Salmonella sp. bacteria which then weakened bacteria would be made into Salmonellosis vaccine. In this study, Salmonella sp. bacteria were isolated directly from ducks’s cloaca by swabs. Salmonella sp. were given UV irradiation treatment with different times of 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes and 35 minutes, with the same distance of 10 cm. Salmonella sp which is irradiated with UV light for 25 minutes is the best, supported by the duck’s immune system increases after 2 weeks of Salmonella infection. This result gives opportunities to develop vaccine for Salmonelosis disease in the duck in the future.