The invention discloses a triple inactivated vaccine for preventing and treating duck circovirus disease, novel duck reovirus disease and duck adenovirus type 3 and a preparation method of the triple inactivated vaccine. The triple inactivated vaccine comprises an effective amount of inactivated antigen and an immunologic adjuvant in immunization, the inactivated antigen comprises a duck circovirus antigen, a novel duck reovirus antigen and a duck adenovirus type 3 antigen. The invention further discloses a method for preparing the triple inactivated vaccine. The 3-type triple inactivated vaccine for preventing and treating the duck circovirus disease, the novel duck reovirus disease and the duck adenovirus disease is good in safety, and mutual interference or influence of antigen components cannot be generated. Immune protection efficacy tests prove that the triple inactivated vaccine can prevent duck reovirus, duck circovirus and duck adenovirus type 3 at the same time, can avoid adverse reactions caused by multiple inoculation immunization, and has the advantages of simple preparation method, convenience, multiple effects, low cost, high vaccine titer content and the like.