Relaxor ferroelectrics are a class of locally disordered crystals possessing peculiar structure and electrical properties. The solid solution of a relaxor perovskite and PbTiO3 (relaxor-PT) exhibits ultrahigh piezoelectric coefficients and electromechanical coupling factors. In order to fully understand the structural origin of this special class of materials' outstanding properties, we propose to carry out a series of low-temperature neutron total scattering experiments and utilize pair distribution function analysis techniques, aiming to investigate the local structures, especially the local polar directions within the polar nano-regions. We will also verify the evolving of the polar nano-regions with increasing temperature, and link them with the change of the electric properties.