E-field- and temperature-dependent domain evolution of lead-free tetragonal (K, Na, Li)(Nb, Sb, Ta)O-3 (KNLNTS) single crystals as well as its corresponding electrical properties have been investigated. When E field is applied along [011](C) direction, (2T) engineered domain structure is formed. Spontaneous polarizations switch under a critical electric field (around 4-5kV/cm), resulting in significant changes in domain structure and great improvement in piezoelectric properties. Furthermore, it is found that piezoelectric constant d(31) and electromechanical coupling factor k(31) of [011](C) poled KNLNTS single crystal decrease with temperature. The extrinsic and intrinsic piezoelectric responses are discussed from the viewpoint of domain structure and lattice distortion, respectively. Our results show that the nanodomain structure relaxes and the lattice distortion declines with temperature, resulting in reduction of extrinsic and intrinsic piezoelectric responses, respectively. Therefore, the piezoelectric instability is ascribed to the decrease of both extrinsic and intrinsic contributions. This work provides a better understanding of domain engineering technique, and the useful information on the improvement of both piezoelectricity and temperature stability of the lead-free piezoelectric materials.