According　to　the　forthcoming　application　of　proton　exchange　membrane　fuel　cell,　the　cell　performances　of　different　temperature　and　pressure　at　low　stoichiometric　ratio　of　reactant　were　experimentally　studied.　The　effect　of　cell　temperature　and　pressure　on　stoichiometric　ratio　of　reactant　was　also　studied.　The　results　indicate　that:　the　cell　performance　at　reactant　stoichiometric　ratio　of　1.0　is　lower　than　that　at　the　condition　of　sufficient　reactant;　when　the　stoichiometric　ratio　reaches　1.3,　the　fuel　cell　can　operate　at　the　excepted　current　steadily;　the　gases　mass　transfer　will　impact　the　stoichiometric　ratio　of　reactant;　when　the　pressure　is　increased　to　0.13　MPa,　the　cell　performance　at　reactant　stoichiometric　ratio　of　1.0　is　as　same　as　that　at　the　condition　of　sufficient　reactant.