Using　low　cost　Al2O3-SiO2　fibre　as　reinforced　phase,　ZL108　alloy　composites　were　made　by　squeeze　casting.　The　composites　and　ZL108　alloy　were　aged　at　different　temperatures,　and　then　examined　by　compression　test.　The　analysis　from　DSC,　EPMA　and　TEM　suggests　that　the　reason　why　after　ageing　at　488K　for　30min　(T6),　the　compression　proof　stress　of　the　composite　with　Vf　20%　fibre　below　573K　was　lower　than　that　of　ZL108　alloy　is　the　reaction　of　Mg　in　the　matrix　and　Al2O3-SiO2　fibre,　which　formed　MgAl2O4,　consumed　a　lot　of　Mg　in　the　matrix,　and　led　to　the　poor　ageing　hardness　and　low　compression　proof　stress.　After　annealing　at　623K　for　720　hours,　the　compression　proof　stress　of　the　composite　is　much　higher　than　that　of　ZL108　alloy,　because　ZL108　alloy　was　produced　over　ageing　at　these　temperatures.　Therefore　the　effect　of　fibre　reinforcement　on　the　composite　was　significant.　At　high　temperature　of　673K,　the　proof　stress　of　the　composite　with　Vf　20%　fibre　was　about　twice　as　high　as　that　of　ZL108　alloy.　At　all　temperatures,　the　proof　stress　of　composite　with　Vf　5%　fibre　is　lower　than　that　of　composite　with　Vf　20%.