Abstract: Quasi-static uniaxial compression experiments and meso compression-shear experiments were carried out toinvestigate the failure properties of polypropylene micro-fiber and steel fiber reinforced cement and concrete composites.Comparing the effects of two kinds of fibers on the composites under these two loading conditions , experimental resultsshow that under quasi-static uniaxial compression , the effects of steel fiber are evident , and those of Polypropylene microfiber are not ; while under compression and shear loading , steel fiber took on evident effects on the strengthening of thematrix in all of the deformation stages , but polypropylene micro-fiber only reinforced the matrix in the stages before failureand can not improve the ultimate shear strength. The debonding and fracture of steel fiber and gravels in the compositeswere observed in the meso experiments. However , the void collapse phenomenon was observed only in local of the cement . The mechanism that void collapse will lead to the formation of the compaction band needs to be revealed in furtherstudies.