Magnesium　phosphate　cement　(MPC)　is　prepared　by　mixing　MgO　powder　(M)　with　KH2PO4　powder　(P)　and　borax　powder　(B).　To　investigate　the　influence　of　calcined　magnesia　on　the　compressive　and　flexural　strength　of　MPC,　two　types　of　magnesia　were　calcinated　under　different　temperatures,　and　the　chemical　and　physical　properties　were　analysed.　The　MPC　was　prepared　by　mixing　calcinated　magnesia　with　fly　ash　and　retarder.　The　selection　principle　of　magnesia　was　proposed　to　optimise　the　physical　and　chemical　properties　of　the　MPC.　The　experimental　results　demonstrate　that　the　increasing　calcination　temperature　led　to　the　increasing　particle　size　of　the　magnesia.　The　calcination　temperature　had　a　significant　influence　on　the　light　magnesia　and　had　no　effect　on　its　chemical　composition.　The　compressive　and　flexural　strength　of　the　MPC　was　tested,　and　its　microstructure　was　analysed　using　XRD　and　SEM　methods.　The　testing　results　demonstrate　that　within　a　certain　range,　the　compressive　strength　increased　with　an　increasing　calcination　temperature.　The　compressive　strength　was　the　maximum　when　the　mole　ratio　of　phosphate　to　MgO　was　1/4-1/5.　In　a　certain　range,　as　the　P/M　decreased,　the　flexural　strength　of　the　MPC　increased　and　subsequently　remained　at　a　certain　level.　(C)　2014　Elsevier　Ltd.　All　rights　reserved.