Uniform precession dynamics and its magnetic damping are investigated in epitaxial Co2Fel-xMnxA1 films by using the time-resolved magneto-optical Kerr effect under out-of-plane configuration.The decay time of uniform precession mode decreases,and thus the magnetic damping increases with the increase of exteal field.Moreover,the decay time decreases as x decreases,so that the enhancement of magnetic damping occurs in Fe-rich sample.Furthermore,the decay time decreases as the excitation fluence increases,which drops rapidly at low magnetic field comparing with the slow reduction at high magnetic field.This unique magnetic damping enhancement is attributed to the enhancement of homogeneous magnetization.