Tungsten　ditelluride　(WTe2)　is　arising　as　an　attractive　material　in　magnetoresistance　(MR)　properties　filed.　The　magnetoresistance　properties　of　WTe2　makes　it　an　ideal　material　for　its　magnetoresistive　heads　of　computer　and　magnetic　sensor　device　applications.　So　far,　people　have　developed　various　controlled　synthesis　methods　to　produce　large-quantity　uniform　flat　WTe2　crystals.　Nevertheless,　none　of　the　methods　are　sustainable,　some　methods　use　reducing　gases,　and　some　use　very　long　heat　preservation,　and　the　process　is　very　complicated.　Here,　a　mild　and　fast　self-flux　method　is　described　for　WTe2　synthesis　that　can　avoid　producing　reducing　gases.　After　conducting　structural　and　physical　tests,　it　is　found　that　annealing　time　is　critical　for　WTe2　structure　formation.　Long　annealing　time　improves　the　crystallinity　of　WTe2　and　makes　its　texture　more　obvious,　increasing　the　conductivity　of　WTe2.　Therefore,　it　will　lead　to　the　anomalous　nonsaturating　positive　magnetoresistance　with　different　field　dependent　behaviors,　reaching　the　ultrastrong　magnetoresistive　value　of　1040%　at　5　K　and　14　T.　The　results　provide　a　sustainable　approach　for　uniform　WTe2　crystal　synthesis,　which　will　benefit　the　large-quantity　production　of　WTe2　magnetoresistive　materials.