Magnesium　silicon　potassium　phosphate　cement　(MSPPC),　a　new　magnesium　phosphate　cement　of　the　MgO-SiO2-K2HPO4　system,　can　possess　higher　strength,　longer　setting　time,　and　better　fluidity　than　the　traditional　magnesium　phosphate　cement　(MPC).　In　MSPPC,　silica　was　an　essential　component,　although　it　is　not　a　primary　material　for　preparing　MPC.　Four　sets　of　specimens　were　designed　and　cast　with　varying　percentages　of　silica　fume　(SF)　to　find　out　the　influence　of　the　silica　fume　content　on　the　setting　time,　fluidity,　compressive　strength,　and　flexural　strength　of　MSPPC.　Experimental　results　showed　that　the　fluidity　of　MSPPC　was　enhanced　with　the　increased　percentage　of　silica　fume,　reaching　its　peak　at　15%　SF.　Silica　fume　significantly　prolonged　the　initial　setting　time　of　MSPPC　from　5.75　min　to　16.50　min　for　20%　SF.　The　compressive　strength　and　flexural　strength　of　MSPPC　at　all　ages　initially　increased,　reaching　their　maximum　when　the　SF　was　15%,　and　then　they　decreased　at　20%　SF.　Based　on　the　pH　value　change,　XRD　analysis,　MIP　analysis,　TG-DSC　analysis,　and　SEM-EDS　observations　during　the　hydration　process　of　MSPPC　system,　the　effects　of　silica　fume　on　the　setting　time,　fluidity,　compressive　strength,　and　flexural　strength　of　MSPPC　were　explained.　©　2019