Catalyst　interface　determines　the　activity　and　stability　of　partial　oxidation　of　methane　(POM)　toward　syngas　under　high　temperatures　crucially.　Herein,　Ni　catalysts　supported　on　CeO　2　were　prepared　under　different　pretreatment　atmospheres　to　construct　an　optimal　and　robust　interface.　Ni/CeO　2　catalyst　pretreated　in　H　2　(Ni/CeO　2　-　H　2　)　exhibits　the　higher　activity　and　the　better　stability　than　Ni/CeO　2　-Ar　and　Ni/CeO　2　-air　catalysts.　The　Ni　-O　-Ce　interfacial　site　in　Ni/CeO　2　-H　2　catalyst　shows　the　lower　reduction　temperature,　indicating　the　enhanced　Hspillover　effect　and　enhanced　oxidation　resistance　of　Ni　under　POM　conditions.　Moreover,　the　XPS　and　in　situ　Raman　results　show　that　Ni/CeO　2　-H　2　contains　more　surface　oxygen　vacancies　for　adsorbing　and　activating　oxygen,　further　contributing　to　the　reaction　activity.　The　in　situ　DRIFTS　results　indicate　that　the　CH　4　could　react　with　the　lattice　oxygen　to　form　formate　and　carbonate,　and　further　decompose　to　CO　and　CO　2　.　These　findings　deepen　the　fundamental　understanding　of　Ni/CeO　2　catalysts　for　POM　reaction.