Improvement of electrocaloric effect was investigated in the lead-free undoped and Mn-doped Ba0.65Sr0.35TiO3 ceramics prepared by spark plasma sintering process. Owing to the merit of spark plasma sintering process, a fully dense undoped and Mn-doped Ba0.65Sr0.35TiO3 ceramics with fine grain sizes could be obtained. The electrocaloric (EC) effect can be significantly enhanced from 0.83 K for conventional sintered Ba0.65Sr0.35TiO3 to 3.08 K for spark plasma-sintered Mn-doped Ba0.65Sr0.35TiO3 ceramics since the dielectric strength was dramatically increased. This work indicated an effective way to achieve the significantly enhanced EC effect in a lead-free system at room temperature.