Abstract Perovskite relaxor ferroelectrics generally possess a microstructural feature, that is, different cations occupying a chemically equivalent position. The ordering degree of these cations is a critical factor for macroscopic properties of relaxor ferroelectrics. Pb(Sc 0.5 Ta 0.5 )O 3 is a classical relaxor ferroelectric and tuning its B‐site ordering degree is of particular interest over years. In this work, we propose a method to directly control the ordering degree of Pb(Sc 0.5 Ta 0.5 )O 3 ceramics during the sintering process by regulating the content of compensated Pb 3 O 4 powder. It is found that the B‐site ordering degree is closely related to the lead vacancies in Pb(Sc 0.5 Ta 0.5 )O 3 ceramics. This work may shed a light on the design of relaxor ferroelectrics with desired B‐site ordering degree.