Abstract: The binding energy of hydrogenic impurities in a cylindrical quantum dot was calculated with the one-dimensional finite-difference method. The effects of the electric field, magnetic field and position of an impurity on the binding energy were studied. When the impurity is located at the center of the quantum dot, the binding energy decreases with increasing electric field and effective radius, and when the impurity is located at the plane normal to the z axis and through the center of the quantum dot, the binding energy changes symmetrically with increasing distance away from the center of the quantum dot. However, when the impurity is located on the z axis, the symmetry vanishes because of the effect of the electric field.