© 2016 Taylor & Francis Group, LLC. In this work, (1−x)Pb(Mg 1/3 Nb 2/3 )O 3 −xPbTiO 3 (PMN−PT) where x = 0.1−0.3 relaxor ferroelectric ceramics were prepared. PMN−PT ceramics were subjected to measurement of dielectric constant by LCR meter by cooling method from 200 to 25°C and investigation subswitching electric field induced strain behaviour was carried out twice, before and after 500°C annealing, by modifiedMichelson interferometric technique at various temperatures (30−70°C). The result showed higher dielectric properties and broad peak at phase transition temperature Tm of ferroelectric to paraelectric, like the nonlinear change of integrated P-E areas and s-E areas around 40 and 90°C for x = 0.1 and 0.2, but the induced strain and integrated s-E area are very sensitive to the annealing effect to observed ferroelectric phase change fromnormal ferroelectric to relaxor phase around 40 and 60°C for x = 0.2 and 0.3.