Dyx（Co40Ag60）100-x (x=0, 0.7, 1.4, 2.1, 2.8, 3.5) granular films have been prepared by DC magneto controlled sputtering method. The XRD data indicated that Dyx（Co40Ag60）100-x films favors the (111) plane preferential orientation. The high annealing temperature t can promote the (111) plane of Ag preferential orientation and Co dissolving in Ag to separate from Ag and accelerate grain growing. Dy element plays the role of a grain refiner and retards the (111) plane preferential orientation result in increasing grains boundary and resistance of films. Magnetic measurements indicated that the value of GMR decreases of all films when annealing temperature is higher 250℃ because of increasing of resistance of films, but it can enhance sensitivityof films doped small Dy element. For small amount of addition Dy to CoAg granular films and proper heat treatment, Dy element can keep the value of GMR a constant and enhance sensitivity. Both maximum values of GMR and sensitivity are -18% and 1.5×10-4 (A/m)-1, respectively.
