The invention provides a clamping device and a pipeline repair system. The clamping device is used for mounting leaking stoppage patches on pipelines and comprises a mounting assembly and a propping part. The mounting assembly comprises a fixing part and a connecting part. The fixing part and the connecting part define a containing area used for at least containing part of the pipeline. The propping part is connected to the connecting part and can move in the containing area relative to the connecting part to prop one leaking stoppage patch. The invention further provides a pipeline repair system. The pipeline repair system comprises the leaking stoppage patch and the clamping device. The leaking stoppage patch comprises a leaking stoppage surface matched with the pipeline in shape and anouter surface getting far away from the leaking stoppage surface and abutting against the propping part of the clamping device. According to the clamping device and the pipeline repair system providedby the invention, the containing area used for at least containing part of the pipeline can be formed on the mounting assembly; the propping part can move relative to the connecting part to enable the propping part to push the leaking stoppage patch to the pipeline, and accordingly, follow-up welding operation is facilitated.