The invention discloses a pipeline pig comprising a middle adapter mechanism. The two ends of the middle adapter mechanism are each connected to a cleaning mechanism comprising a support shaft hingedto the middle adapter mechanism; the outer ring of the support shaft is in dowel joint with a fixed baffle fixedly, and one side of the fixed baffle is provided with a spring which is in dowel joint with the support shaft movably; the other end of the spring is provided with a lantern ring regulated with the support shaft movably, and first support rods distributed in an array along the axis of the lantern ring are hinged to the outer ring of the lantern ring; and a first mounting disk which is in dowel joint with the support shaft fixedly is hinged to the other end of each first support rod.The pipeline pig is simple in structure, and convenient and efficient in operation; a traditional bowl cup is replaced with a valviform cup; materials are saved, and the cost input is reduced; meanwhile, blocking materials in a pipeline are enabled to flow, and the internal pressure of the pipeline is prevented from being increased; meanwhile, the pipeline pig is applicable for cleaning of pipelines of different pipe diameters as well as cleaning of pipelines of narrow inner diameters due to damage; and the blocking phenomenon of the pipelines is avoided.