The　(Al0.1Ga0.9)(0.5)In0.5P,　four-element　alloy,　whose　band　is　direct,　is　used　to　make　optoelectronic　devices.　The　wavelength　of　the　material　is　about　630nm.　When　it　is　epitaxially　grown　by　low　press-metalorganic　chemical　vapor　deposition(LP-MOCVD),　its　quality　will　depend　on　temperature,　one　of　the　most　important　conditions.　So　it　is　essential　to　find　out　the　best　temperature　of　growth.　The　quantum　wells　of　the　(Al0.1Ga0.9)(0.5)In0.5P　are　grown　at　700　degrees　C,　680　degrees　C,　670　degrees　C　and　660　degrees　C　respectively.　The　best　temperature,　which　is　found　out　by　the　results　of　photoluminescence　PL,　is　about　670　degrees　C.　The　reasons　are　given　by　the　results　of　PL,　surfaces　of　wafers　and　the　flow　field　simulation　of　MOCVD.　The　revaporization　of　In　at　high　temperature　and　the　incorporation　of　O　at　low　temperature　can　lead　to　bad　quality.　An　available　path　to　solve　growth　at　high　temperature　is　to　increase　the　effective　density　of　In.