Different　from　making　ordinary　magnesium　phosphate　cements　(MPCs)　with　potassium　dihydrogen　phosphate　(KH2PO4,　PDP),　magnesium　oxide　(MgO,　M)　and　borate　as　retarder,　a　novel　high-strength　Magnesium　Silicon　Potassium　Phosphate　Cement　(MSPPC)　created　by　mixing　dipotassium　hydrogen　phosphate　(K2HPO4,　DHP　(P)),　silica　fume　(SF),　MgO　and　Water　(W),　without　the　use　of　a　retarder,　is　proposed　for　the　first　time　in　this　study.　The　mechanical　properties　of　several　MSPPC　mixtures　prepared　with　different　proportions　of　P/M　(weight　ratio　of　K2HPO4　to　MgO),　W/C　(weight　ratio　of　water　to　cement　paste　(C　=　P　+　M　+　SF))　and　mass　fraction　of　silica　fume　were　investigated.　The　hydration　reaction　mechanism　of　MgO-SiO2-K2HPO4　system　was　analyzed　with　a　variety　of　techniques　including　pH,　X-ray　diffraction　(XRD),　environmental　scanning　electron　microscope-energy　dispersive　spectrometer　(ESEM-EDS)　and　thermo-gravimetric　and　differential　scanning　calorimeter　(TG-DSC).　The　results　show　that　the　cement　paste　with　P/M　of　1/3,　15　wt%　SF　and　W/C　ratio　of　0.16,　the　compressive　strength　was　measured　to　be　113.16　MPa.　The　maximum　flexural　and　compressive　strength　of　MgO-SiO2-K2HPO4　system　is　16.82　MPa　and　101.26　MPa　respectively,　which　is　higher　than　those　of　MgO-K2HPO4　system.　In　MgO-K2HPO4　system,　the　reaction　generates　a　large　amount　of　Mg(OH)2　with　poor　gelation　and　expansion,　and　a　small　amount　of　hydration　product　MgKPO4·6H2O　(MKP)　with　low　internal　crystallinity,　so　the　structural　strength　is　very　low.　Inversely,　in　MgO-SiO2-K2HPO4　system,　silica　fume　plays　an　important　role,　and　the　active　silicon　components　in　silica　fume　are　fully　involved　in　the　acid-base　reaction,　improving　the　mechanical　properties　and　compactness　of　microstructure　of　MSPPC.　Main　hydration　product　struvite-K　has　good　crystallization,　compact　accumulation,　high　density　of　cross-section　structure　and　good　structural　integrity　of　MSPPC.　Expected　secondary　hydration　products　are　magnesium　silicate　gel　(e.g.,　MgSiO3)　and　amorphous　silicon　phosphate　phases,　contributing　to　the　strength　in　MSPPC　pastes.　©　2019　Elsevier　Ltd