First　possession　is　a　common　heuristic　people　use　to　solve　property　conflicts.　Previous　studies　examined　whether　young　children　judged　ownership　based　on　the　first　possession　heuristic　and　its　stability　when　conflicting　with　other　cues　such　as　labor,　but　few　focused　on　the　effects　in　the　discovery　context.　In　this　study,　we　used　two　discovery　stories　which　indicate　the　discovered　object　was　not　owned　by　anyone　beforehand　and　investigated　ownership　reasoning　with　the　first　possession　heuristic　in　Chinese　3-　to　6-year-old　preschoolers.　By　pitting　the　first　possession　cue　against　the　labor　cue,　we　investigated　the　stability　of　the　first　possession　heuristic　in　young　children＇s　ownership　reasoning.　The　results　showed　that　in　the　condition　where　there　was　only　the　first　possession　cue,　both　the　younger　and　older　groups　used　the　first　possession　heuristic　to　reason　about　ownership.　However,　in　the　labor　condition,　5-　and　6-year-olds　ceased　to　support　the　first　possessor　and　turned　to　assign　objects　to　the　laborer,　whereas　3-year-old　children　still　insisted　on　the　first　possession　heuristic　(Study　1　and　Study　2).　Children　across　four　age　groups　did　not　assign　ownership　to　the　person　who　just　played　with　the　object　but　did　not　modify　it　(Study　2).　The　results　demonstrate　that　Chinese　preschoolers　understand　the　role　of　first　possession　in　ownership　assignment　at　an　early　age　in　the　discovery　context　but　the　elderly　preschoolers　do　not　rely　on　the　first　possession　cue　when　there　are　conflicting　cues　such　as　labor.