The invention discloses a triple polymerase chain reaction (PCR) detecting primer group, a reagent kit and a method for diagnosing grass carp reovirus. The method disclosed by the invention is a triple RR-PCR detecting method capable of simultaneously detecting three kinds of subtypes of the grass carp reovirus: HZ08 strain types, 104 strain types and JX09-01 strain types, the subtypes of the grass carp reovirus can be identified when the grass carp reovirus is detected, the valuable time is obtained for the providing of prevention and control measures in a targeted way and more precise treatment according to diseases, and the important significance is realized on the effective control of grass carp bleeding diseases. When being applied to the detection of the grass carp reovirus, the primer group and the reagent kit disclosed by the invention have the advantages of accuracy, flexibility, high speed, cost saving and the like.