Effects of different calcining degree coal-gangue on fluidity and strength of cement paste were investigated,and the microstructures of coal-gangue and cement paste with coal-gangue were analyzed by SEM.Results show that the structures of calcined coal-gangue and non-calcined coal-gangue are different,the former is loose and porous and the latter is compact;the water-absorption ratio of coal-gangue increases and the fluidity of cement paste with coal-gangue decreases with the prolonging of calcining time of coal-gangue;the strength of cement paste with calcined coal-gangue is higher than that of cement paste with non-calcined coal-gangue,but it is not certain if the prolonging of calcining time of coal-gangue is benefitial to the strength of cement paste with coal-gangue,or even has adverse effect.