It　is　a　new　technology　for　High　Temperature　Air　Combustion　(HTAC)　that　saves　energy　and　protects　environment.　The　unsteady　status　under　high　temperature　and　low　oxygen　concentration　of　a　certain　burner　is　numerical　simulated　by　considering　the　inlet　channel　of　the　gas　and　preheated　air　both　in　the　same　direction　and　in　the　inverse　direction　in　this　paper.　The　highest　temperature　zone　enlarge　with　the　decrease　of　O2　Mass　Fraction　and　the　temperature　field　becomes　more　uniform　whatever　the　inlets　of　fuel　and　air　are　in　the　same　direction　or　in　the　inverse　direction.　The　average　temperature　when　the　inlets　of　fuel　and　air　are　in　the　same　direction　is　higher　than　that　when　the　inlets　of　fuel　and　air　are　in　the　inverse　direction.　The　difference　of　the　average　temperature　increases　gradually　with　the　change　of　time.　The　highest　temperature　and　the　average　NOx　Mass　Fraction　reduces　with　the　decrease　of　O2　Mass　Fraction.　The　average　value　when　the　inlets　of　fuel　and　air　are　in　the　same　direction　is　about　30-50　K　higher　than　that　when　the　inlets　of　fuel　and　air　are　in　the　inverse　direction.　But　under　high　oxygen　concentration,　the　average　NOx　Mass　Fraction　when　the　inlets　of　fuel　and　air　are　in　the　inverse　direction　is　more　than　that　when　the　inlets　of　fuel　and　air　are　in　the　same　direction.　High　Temperature　Air　Combustion　under　low　oxygen　can　make　the　average　temperature　increase　30-50　K,　and　do　not　increase　the　emission　of　pollutants.