A tracking system composed of three multiwires proportional chambers (MWPCs) for the exteal target facility of the Cooler Storage Ring is reported in this paper.The active areas of the MWPCs are 518 mm × 400 mm,582 mm × 450 mm,and 710 mm × 500 mm.Each MWPC consists of a series of alteately placed cathode and anode wire planes and can measure position along the directions of-30°,0°,and 30° relative to horizontal.The construction and operation of the detectors are described,and a method for track reconstruction is introduced.A track-finding efficiency of about 62％ and a spatial resolution of 1.21 mm have been achieved.The pion and proton can be identified clearly with the tracking system combined with a time-of-flight system.