The effect of styrene-butadiene latex(SBL) on the water absorption ratio and the carbonization depth of cement mortar were studied.The prediction models of water absorption ratio,carbonization depth correlating with many factors were proposed.The micro-pore parameters,included open porosity,close porosity and total porosity,pore size distribution and characteristic pore diameter of cement mortar modified by SBL were tested.The microstructure of cement mortar was studied by SEM.The results show that with the additive of SBL,the water absorption ratio and the carbonization depth of cement mortar decrease greatly.When the content of SBL exceed 3%(the ratio of total styrene-butadiene latex to cement),the pores with size below 20 nm increase markedly,while the pores with size exceed 50 nm decrease markedly.The mean pore diameter,mode pore diameter and median pore diameter decrease in large degree with the increasing of SBL.The open porosity decreases and the close porosity increases markedly,while the total porosity changes little with the content of SBL exceed 6%.