A plug-in box and plug-in card thereof. The plug-in card comprises a single board and a plurality of heat sinks mounted on the single board. The plurality of heat sinks are arranged in a flowing direction of an air flow of the plug-in card, and each of the plurality of heat sinks comprises a plurality of main fins, wherein main body plates of the plurality of main fins on each of the heat sinks are disposed in parallel, and the distance between two neighboring main body plates on each of the heat sinks is sequentially reduced in the flowing direction of the air flow.
