Ar/39 Ar isotopic chronologic studies of intrusive rocks from Tongling area show that ages of these rocks are all younger than 140Ma and belong to Late Yanshanian period, with granodiorite, quartz monzodiorite, pyroxene monzodiorite and gabbro diabase being 139.8-137Ma, 137-135.8Ma, 138.2-136.6Ma and 133.7Ma respectively. On the basis of 40 Ar/39 Ar isotopic chronologic studies of these intrusive rocks, the authors have also dealt with their K Ar and Rb Sr isotopic ages, and pointed out that the age error was caused by the late hydrothermal alteration and the mixture between mantle magma and crustal magma. In addition, the mineralization ages are found to be close to the smaller ages in 40Ar/39 Ar age spectra, which is in accord with the regional metallogenic character that mineralization took place later than magmatic activity.