Magnesia-phosphate　cement　(MPC)　is　a　new　type　of　cementing　material　composed　of　magnesia　powder,　phosphate　and　boric　acid　retarder　in　a　given　proportion.　In　order　to　study　the　influence　of　calcined　magnesia,　fly　ash　and　boric　acid　retarder　on　the　performance　of　MPC　under　different　conditions,　magnesia　was　calcined　and　mixed　with　fly　ash　and　retarder　in　various　mixtures　to　prepare　different　MPC　samples.　The　compressive　strength,　hydration　mechanism　and　microstructure　of　MPC　were　assessed.　The　results　show　that,　within　a　certain　range,　the　compressive　strength　of　MPC　increases　with　increasing　calcination　temperature　and　increasing　holding　time　of　the　calcined　magnesia.　The　addition　of　fly　ash　improves　the　microstructure　of　MPC　and,　in　a　certain　range,　the　compressive　strength　of　MPC　increases　with　an　increase　in　fly　ash　content.　Boric　acid　reduces　the　compactness　of　MPC,　thus　decreasing　the　compressive　strength.