The　paper　delivered　the　physical　properties　and　fracture　morphology　of　cement　mortars　modified　by　two　kinds　of　polymer　powder.　Test　results　showed　that,　both　hydroxyethyl　methyl　cellulose(M)　and　vinyl　co-polymer(D)　could　make　cement　mortars　possess　excellent　water　retention,　and　only　very　small　additions　were　required　for　this　purpose,　thus　enhancing　workability　and　ensuring　that　the　water　remained　present　for　uniform　setting　and　hardening.　The　air　incorporated　by　M　or　D　can　efficiently　improve　pore　structure　of　hardened　mortars,　thus　the　modified　mortars　were　of　lower　capillary　water　adsorption.　The　additions　of　the　M　and　D　should　be　in　certain　scope.　Polymer　modified　cement　mortars　were　suitable　to　be　produced　as　dry-mixed　mortars　in　plants,　and　their　different　additions　of　polymer　can　meet　the　different　requirements　to　certain　types　of　modern　construction.