Asubspaceprojectedconjugategradientmethodisproposedforsolvinglargeboundconstrainedquadraticprogramming.Theconjugategradientmethodisusedtoupdatethevariableswithindicesoutsideoftheactiveset,whiletheprojectedgradientmethodisusedtoupdatetheactivevariables.Ateveryiterativelevel,thesearchdirectionconsistsoftwoparts,oneofwhichisasubspacetrumcatedNewtondirection,anotherisamodifiedgradientdirection.Withtheprojectedsearchthealgorithmissuitabletolargeproblems.Theconvergenceofthemethodisprovedandsamenumericaltestswithdimensionsrangingfrom5000to20000aregiven.