We investigated the effects of the irradiation of light-ions on the superconducting $MgB_2$ thin films fabricated by using HPCVD. Deuterium and helium ions were irradiated on $MgB_2$ thin films by various doses, from $1{ imes}10^{10}cm^{-2};to;8{ imes}10^{15}cm^{-2}$. During these experiments some reasonable results and unpredictable results have been obtained. The reasonable results are that the peak of the reduced maximum pinning force shifts by increasing the pinning sites in $MgB_2$ films and the slightly change of critical current density of films. We obtained some unusual results, which are the increasing of the transition temperature and the change of residual resistance ratio. Among the data of deuterium and helium ion irradiation experiments, the results of helium ion irradiation have most notable points so we will discuss mainly about helium irradiation experiments.