The invention relates to a spiral pipe inner wall weld joint grinding mechanism. The spiral pipe inner wall weld joint grinding mechanism comprises a supporting device, a grinding feeding device and agrinding executing device; the supporting device is used for supporting the grinding feeding device on the inner wall of a pipeline, and guaranteeing the stability and accuracy of the grinding feeding device; the grinding feeding device is used for installing the grinding executing device and provides moving on the axis, turning over around the axis and radial telescopic movement for the grindingexecuting device; and the grinding executing device is used for achieving the grinding operation on the inner wall of the pipeline. The spiral pipe inner wall weld joint grinding mechanism solves theproblems caused by stirring friction welding, and achieves automatic grinding operation on the inner wall of the pipeline.