Abstract: The Ordovician in north China platform consists of marinecarbonate rocks .As oil and gas resrvoirs. They are formed by the combination of sedimentation. tectonism and diagenesis. Three sets of reservoir were formed duringgeo history .The first type of reservoir region is paleo一weathered and teached rocks .They occur in the centrat part of Ordos Mesozoic and Cenozoic fault depressions in east of the Taihang montain which distributed from the 109. 3 E to the 39 N area The second type of the reservoir are deep fault rock solution zones. which are mostly developed along Yanshan or Himalaya fault zone. They mainly occur in the sourth一western margin .The third type of reservoir is evaporating strand flat solution reservoir .which mainly occours in the central一eastern part of the Ordos. The three resaervoirs can be divided into five types and their occurrences can be determined. 1. The ordivician dolomite reservoirs formed by the sedimentation. 2. Then dolomite and solution collapse reservoir formed by the sedimentation and the Caledonian tectonism .3. The carbonate rock reservoir formed bt the sedimention and the Indosinian一Yanshan tectonisms. 4. The carbonate rock reservoir formed by the sedimentation and the multiple cyclic tectonism. 5. The solution pore and cavity doiomite reservoir formed by the sedimentation一diagenesis and Huaiyuen teotonism .The practices of the oil and gas exploration and production have prvoren that the oil reserrvoir can be formed be formed by the combination of the ordivician carbonate rock reservoirs and the Mesozoic一Cenozoic hydrocarbon .It is important to study the ordivician carbonate rock reservoirs to the hydrocarbon exploration of the Ordos.