In this paper, we have considered the energy spectra and quadruple transition probabilities of even-even Er isotopes via partial dynamical symmetry in interacting boson model framework. The advantage of using interactions with a partial dynamical symmetry is that they can be introduced, in a controlled manner, without destroying results previously obtained with a dynamical symmetry for a segment of the spectrum. Partial dynamical SU(3) symmetry has an accurate description for nuclei which exhibit rotational deformed structure because of removing undesired degeneracies from energy spectrum of them.The agreement with the most recent experimental counterparts is acceptable. Also, there are some suggestions about the reduction of uncertainty with increasing the neutron number and quadrupole deformation parameter.