Paraelectric K0.99Li0.01Ta1−xNbxO3 (x = 0.38, 0.39, 0.40) lead-free single crystals have been grown by the top-seeded solution growth method. All the crystals have Curie temperature (Tc) close to room temperature (RT), and possess large relative dielectric constants near Tc. A scanning Michelson interferometer was used to investigate the electrostrictive (ES) behavior of the crystals. The crystals show pure ES characteristics and large electrosrictive coefficients. The ES coefficient Q11 of K0.99Li0.01Ta0.60Nb0.40O3 reaches as high as 0.12 m4/C2, about six times of the value of Pb(Mg1/3Nb2/3)O3 ceramics.