Abstract: Oxidation resistant aluminized layers on the TZM Mo-based superalloy surface were prepared by pack cementation technique at 1 050 ℃ for 12 h.The microstructure,phase composition and element distribution of the layers were analyzed by means of SEM,EDS and XRD.The hardness and high temperuture oxidation resistance of the layer were discussed.The results show that the phase composition of the layers were Al5Mo,Al3Mo and Al4Mo.The layer with double layer structure was uniform and compact,whose thichness was 130 μm and had a good metallurgical bonding with the substrate.The hardness of the aluminized layer with granular surface was 8 000 MPa.The pack cementation aluminized layer had good oxidation resistance after oxidizing at 800 ℃ for 80 h.