In the present work, we have studied the effect of impurity position on energy levels, the donor binding energy and third harmonic generation of a pyramid and a cone like quantum dot. For this goal, we have calculated the energy levels, wave functions and binding energy using finite element method for various impurity positions. Our results show that the impurity location plays an important and considerable role in the electronic and optical properties in a pyramid and a cone like quantum dot. We found that the third harmonic generation and binding energy of both quantum dots have a maximum value at a special impurity position. The special impurity location is different for the two quantum dots. Also, we have deduced that the third harmonic generation of a cone like quantum dot is larger than a pyramid quantum dot for same volumes and heights.