Prx(Co40Ag60)100-x (x=0, 0.5, 1, 1.5, 2, 3) granular films were prepared by a DC magnetron sputtering method. The XRD data indicate that Pr element can promote Co dissolving in Ag to separate from Ag and favors the (111) plane preferential orientation. Giant magnetoresistance (GMR) measurements indicate that the value of GMR increases at first and then decreases with increase of Pr content and the peak value appears at x=0.5-1.0 when the annealing temperature is below or equal to 250 oC. Proper addition of Pr to CoAg granular films can enhance GMR effect and the sensitivity to the magnetic field, whose maximum values are –14.34% and 0.67×10-3 (A/m)-1, respectively.