Deep　understanding　of　the　influence　and　mechanism　of　A-PAM　on　the　early　properties　of　the　cement-based　materials　is　of　both　scientific　and　practical　importance.　In　this　paper,　the　effects　of　anionic　polyacrylamide　(A-PAM)　with　different　mass　ratios　on　the　early　properties　of　cement,　including　hydration,　structural　build-up,　setting　time　and　early　strength　development　were　studied.　The　interaction　between　A-PAM　and　cement　particles　was　also　investigated.　The　relationship　between　the　adsorption,　retardation　of　A-PAM　and　the　early　properties　of　cement　paste　was　then　discussed.　The　results　showed　that　the　retardation　and　bridging　effect　generated　from　A-PAM　jointly　affect　the　early　performances　of　cement.　A-PAM　can　be　adsorbed　onto　the　surface　of　cement　particles　until　a　saturation　point　is　reached.　When　the　A-PAM　dosage　is　below　the　saturation　point,　A-PAM　mainly　acts　as　flocculant,　bridging　cement　particles　and　increasing　the　connection　between　cement　particles.　This　accelerates　the　structural　build-up　and　setting　of　cement　paste.　When　the　A-PAM　dosage　is　above　the　saturation　point,　the　dominant　role　of　A-PAM　is　retarder,　which　highly　retards　the　cement　hydration　and　setting,　thus　slows　down　the　structural　build-up　and　reduces　the　early　strength.