Co_(87)Nb_(10)Zr_3, Co_(76)Nb_(19)Zr_5, Co_(64)Nb_(26)Zr_(10) and Co_(64)Nb_(16)r_(20) amorphous films were deposited on noncrystalline glass substrates by DC unbalanced magnetron sputtering. The compositions of amorphous films were tailored in the light of the individual deposition rate of Co, Nb and Zr. The amorphous films with the anticipated composition were prepared by means of co-sputtering Co, Nb and Zr targets simultaneously, it is indicated that there is interaction among three targets during co-sputtering. The morphology and composition of the films were observed by SEM, AFM and EDS. The structure and magnetic property were measured by XRD and physical property measurement system (PPMS). The coercivity changes with the composition, varying from 240 to 1 600 A/m. After vacuum isothermal annealing at temperatures of 475, 500, 525 and 550 ℃ for 15 and 30 min, respectively, it is found that high Nb content is beneficial to improving thermal stability of amorphous films. The crystallized films have the mean grain size of 2-19 nm.