We report here on the effect of Xe+ ion irradiation on the magnetic properties of amorphous CoTi thin films. With increasing fluence range the in-plane Kuor perpendicuIar anisotropy Kpdecreases continuously and disappears for 5×1015Xe+/cm2, while the magnetization remains unchanged. Resonance measurements shows that even for low fluences the homogeneity along the film thickness is improved. In comparison with thermal annealing the much higher efficiency of ion irradiation in order to suppress Kuis displayed. Discussions on the physical origin of Kuare also given.