The magnetoresistance (MR) of (Co/C r) 70 superlattice with hcp-Co layers and bcc- Cr layers on both MgO and Al2O3 substrates with MO as a buffer layer, and the anisotropy magnetoresistance (AMR) of the single-crystal hcp-Co, fee-Co, as well as the CoCr alloy thin films have been studied at 10 K and 295 K, respectively. The MR of Co/Cr multilayers has been observed to increase by a factor of 3.8 with replacing its substract MgO(100) by Al2O3(1102) only. The AMR of Co films has been found to decrease rapidly by the buffer layer as well as the alloying effect between Co and Cr.