La2Mo2O9　is　expected　to　have　an　extremely　low　thermal　conductivity.　However,　the　alpha-beta　phase　transition　at　580　degrees　C　seriously　affects　its　performance　and　applications.　In　this　work,　a　series　of　La2-xGdxMo2O9　(x=0.0　similar　to　0.5)　solid　solution　was　prepared　by　doping　La2Mo2O9　with　Gd2O3,　and　the　effect　of　Gd3+　doping　on　the　phase　stability　and　thermal　conductivity　was　investigated.　The　results　show　that　the　phase　transition　of　La2Mo2O9　is　effectively　suppressed　with　the　doping　of　Gd3+　ions.　The　samples　show　a　beta-phase　when　x　＞=　0.2.　Moreover,　the　thermal　conductivity　decreases　firstly　and　then　increases　with　the　increase　of　doping　content　of　Gd3+　ions,　reaching　a　minimum　value　at　x=0.2　at　room　temperature.　The　thermal　conductivities　of　all　samples　are　below　1　W/(m.K).