A sealing structure of a top cover of an overhead high-votlage equipment box of an EMU is disclosed, A high-votlage equipment box comprises a box body, A top cover is arranged on the box body, A double-layer sealing structure is adopted between the top cover and the box body, A seal rubber strip is bonded on the box body and the top cover, The sealing rubber strip comprises a first sealing strip and a second sealing strip, and a stepped structure is formed in the vicinity of the edge of the top cover, and comprises a first step and a second step higher than the first step from the outside to the inside. The first sealing strip is positioned between the first step and the box body, and the second sealing strip is positioned between the second step and the box body. The sealing structure ofthe invention is stable, when the train is running at high speed, external water molecules do not enter the box body. The cabinet isolates the external environment, ensures the normal operation of the electrical components in the cabinet, while ensuring the rigidity, the lightweight design requirements can be maximized to meet the requirements of high-speed EMUs.