Alumina-supported Schiff base manganese complexes were synthesized by reaction of Schiff base manganese complexes with alumina, and were characterized by means of IR, UV-Vis and XPS. The supported complexes were used as catalysts in oxidation of cyclohexane. Effects of Schiff base manganese complex structure, catalyst dosage, oxygen pressure and reaction temperature on oxidation of cyclohexane were studied. The supported catalysts are better in stability than the unsupported because they can be easily separated from products and can be reused after purifying and drying. The catalytic activity decreases with the increase of cavity within complex molecules. N,N＇-bis （salicylic aldehyde ） ethylenediamine Schiff base manganese complexes supported on Al_2O_3 （[Mn（Salen）（1）]-Al_2O_3 ） is the best in catalytic activity. Under the optimal conditions for cyclohexane oxidation： [ Mn （ Salen ） （ 1 ） ]-A12O3 mole fraction 0.30% , oxygen pressure 1.4 MPa, reaction temperature 140 ℃ and reaction time 4 h, conversion of cyclohexane and selectivity to KA oil （mixture of cyclohexanol and cycohexanone）are 10.8% and 84.2% respectively, and number of average molecules of cyclohexane converted per each active center on catalyst is 3600.