Modified　bagasse　retarder　(MBR)　was　prepared　by　sodium　chlorite　pretreatment　and　compound　acid　hydrolysis　of　bagasse　in　the　presence　of　a　catalytic　amount　of　phosphotungstic　acid.　The　structure　was　analyzed　by　FTIR.　The　influence　of　MBR　on　the　cement　hydration　was　analyzed　by　hydration　heat,　XRD　and　SEM.　The　retarding　effects　of　MBR　and　sodium　gluconate　(SG)　were　compared　at　20　and　50,　respectively.　The　results　showed　that　MBR　contained　hydroxyl　group,　carboxyl　group　and　phosphate　group,　which　had　good　adaptability　to　cement,　exhibited　better　retarding　performance　than　SG.　MBR　did　not　affect　the　later　compressive　strength　of　concrete,　which　could　delay　the　induction　period　and　reduce　the　hydration　rate　in　accelerating　period.　©　2021,　Editorial　Office　of　FINE　CHEMICALS.　All　right　reserved.