Lead-free 0.96K0.5Na0.5NbO3–0.04LiTaO3 ceramics modified with different amounts of SrTiO3 (ST) from zero to 10mol% were prepared by normal sintering. It was found that ST modification changed the crystal structure from orthorhombic to tetragonal and for ceramics with 10mol% ST, pseudocubic structure was formed which was nonpolar. Investigation of bipolar strain revealed that with increasing ST content to 7.5mol%, the negative strain decreased. This observation was attributed to the existence of nonpolar regions with local composition close to that of the ceramic containing 10mol% ST. This phenomenon was accompanied with strain enhancement in unipolar strain curve because of the contribution of strain due to electric field-induced transition from nonpolar to ferroelectric phase, in addition to electric field induced strain.