Abstract: The reservoir characteristics of the Ordovician carbonate rocks from cores in the Jiyang Depression and outcrops from the West Shandong Rise were studied systematically by means of techniques of casting,slicing and cathodoluminescencing, etc. The results showed that the primary porosity was almost lost, the secondary porosities and fractures were preponderant now. The fractures developed in all formations, but they were more prominently in dolomite formation than that in limestone. The tectonic fractures were most preponderant among all fracture types and they always occurred in the fold axis or nearby the fault belts, while the dissolution fractures were often discovered beneath the unconformities. The intracrystal porosity, intercrystal dissolution porosity and vugs were dominant reservoir space in the dolomite rocks. The reservoirs developed mainly in the sections of dolomite rocks of Majiagou Formation and a few in limestone, with types of reservoir space being mainly moldic, interparticle and dissolution porosities. The dissolution breccia and bedded crystallization limestone occurred in the top of Badou Member of Majiagou Formation, with major types of porosity being intragravel,intracrystal and vugs. It might be very important for exploring reservoir in dolomite rocks. Tectonics, lithology and diagenesis should be the key factors controlling the vertical distribution of reservoir of the Ordovician carbonate rocks in the Jiyang Depression and the West Shandong Rise.