• A strategy of donor-acceptor (Sm-Mn) co-doping defect engineering is introduced into the PMN-PT to improve the d 33 and Q m simultaneously. • The Optimal performances were obtained in PMN-30PT: 2.5Sm, 1-2Mn ceramics, with d 33 =860-543 pC/N, Q m =495-754, and tan δ =0.0055-0.0086. • This high performance originates from the combined effects of ( Mn Ti ″ − V o • • ) x defect dipoles and the local structural heterogeneity. PbTiO 3 -based piezoelectric ceramics are key materials for developing various electromechanical transducers. For high-power ultrasonic transducers, piezoelectric ceramics are required to possess large piezoelectric coefficient ( d 33 ) and high mechanical quality factor ( Q m ). Although acceptor dopants can improve Q m , they also deteriorate d 33 . If suitable piezoelectricity-beneficial donor dopants can be introduced into acceptor-doped ceramics, it is very possible to obtain large d 33 and high Q m simultaneously in donor and acceptor co-doped ceramics. In this work, a series of x mol% Sm and y mol% Mn co-doped Pb(Mg 1/3 Nb 2/3 )O 3 -30PbTiO 3 (PMN-30PT: x Sm, y Mn) ceramics were prepared by the solid-phase sintered method. The crystal structure, local domain structure and electromechanical properties were systematically analyzed. Optimal performances were obtained in PMN-30PT: 2.5Sm, 1-2Mn ceramics with d 33 =860-543 pC/N, Q m =495-754, and dielectric loss tan δ =0.0055-0.0086. This high performance originates from the combined effects of ( Mn Ti ″ − V o • • ) × defect dipoles and the local structural heterogeneity.