As　the　key　material　used　in　high-speed　railway　to　reduce　vibration　in　the　slab　track,　CA　mortar　mainly　includes　cement,　asphalt　emulsion　and　multiple　additives.　Among　all　additives,　water　reducer　is　the　important　component.　In　order　to　study　the　influences　of　water　reducer　of　different　types　and　additions　on　the　strength　and　micro-structure　of　CA　mortar,　three　kinds　of　water　reducers　of　polycarboxylate,　naphthalene　sulfonate　and　wood　series,　were　used　with　different　additions　to　investigate　their　influences　on　the　strength　of　CA　mortar,　meanwhile,　the　micro-structure　were　observed　by　SEM　method.　The　results　show　that,　the　polycarboxylate　water　reducer　has　the　lowest　effect　to　decrease　the　CA　mortar　strength.　When　the　types　of　water　reducer　are　the　same,　the　more　the　water　reducer　are,　the　more　the　strength　decrease.　By　the　SEM　observation,　the　reasons　of　strength　changing　of　different　CA　mortars　can　attributed　to　the　differences　of　the　pore　volume,　pore　size　and　pore　connectivity.