Abstract: The effect of impurities on the Rutherford scattering experiment was analyzed numerically based on the Monte Carlo method. The positions of target atoms in the crystal lattices were replaced by impurity’s atoms and it is proportional to the purity quotient of target. Taking into account the effect of impurity, the results show that the presence of impurity leads to a new peak in the angular distribution of the outgoing particle and the location of this new peak moves to the larger angle with increasing atomic number. Meanwhile, the lower the atomic number and the higher the content of the impurity element are, the more contribution to the formation of newly angular distribution peak is. At the same time, lower average energy of incident particles results in significant effect of the impurity. In addition, the analysis results of the typical heavy ion beam of C⁶⁺ and N⁷⁺ on the Rutherford scattering experiment with the presence of impurities indicate that improved distinguishability could be obtained comparing with the α particle.