The invention is applicable to the technical field of vaccine preparation, and provides a preparation method of inactivated vaccine for preventing duck reovirus. The method comprises the following steps: step 1, selecting standard viral species; step 2, preparing the standard viral species into viral species for production; step 3, preparing an antigen preparation material and preparing antigen according to the viral species for production; step 4, detecting the antigen and performing concentration inactivation on the antigen. The method has the advantages that inoculation is only required tobe performed before breed ducks start laying, the inoculation dosages of two vaccines are respectively 1ml and 0.8ml for one duck, after vaccination is performed about 21 days, hatching eggs can be collected for hatching, by taking that the protection rate of duck reovirus of ducklings is greater than 98 percent as a standard, hatching egg utilization cycles of the two vaccines after vaccination are respectively 6 weeks and 9 weeks after vaccination, immune vaccines are enhanced again after 6 weeks and 9 weeks after vaccination of the two vaccines, and the dosages are the same, the vaccines are repeatedly inoculated till the breed ducks are eliminated, and the preventive effect on liver and spleen necrosis caused by infection of the duck reovirus of the two vaccines with two types of adjuvant are exact.