A heat exchanger and an integral sealing device (100, 200, 300, 400, 500) used for a manifold (10, 10′) in the heat exchanger. The manifold (10, 10′) on one side of the heat exchanger includes two pipelines (11, 12, 11′, 12′) which are parallel to each other and communicated with each other. A first bore (13) and a second bore (14) are formed in two pipelines (11, 12, 11′, 12′) due to a drilling process. The first bore (13) is used for enabling refrigerant to flow from a cavity of one of two pipelines (11, 12, 11′, 12′) into a cavity of the other pipeline. The second bore (14) is a process hole left by the drilling process, and the integral sealing device (100, 200, 300, 400, 500) seals the process hole.