Abstract: The activation temperature of spent oil shale and its relation with pozzolan activity is discussed and the problem of using water-reducer as grinding aids is studied.A new technique for producing No.425 and No.325 quality Portland-Pozzolan cement by increasing the spent oil shale admixture to 40～50% without changing the current production process is proposed This will expand the use of spent oil shale,relieve environmental pollution and increase the economic benefits from the oil shale industry.