Abstract <p>Piezoelectric structure stands as smart sensors (or actuators) in control systems or high-efficient energy harvesters in powering engineering which have aroused significant interests, and the structural dynamic responses analysis is crucial to avoid unwanted vibrations. This work aims to study the transient thermo electromechanical responses of a two-dimensional orthotropic piezoelectric plate of crystal class mm2 with quadratic temperature-dependent thermal conductivity. The nonlinear governing equations are established based on the L-S piezoelectric thermoelasticity, and thermal conductivity is adopted as the quadratic function of the temperature. To solve the nonlinear solutions, the nonlinear time-domain finite element method is developed to directly solve nonlinear finite element governing equations, of which maximally avoids the precision losses within the applications of the integrated transformation method. Numerical results reveal that quadratic temperature-dependent thermal conductivity remarkably affect nonlinear transient thermo-electromechanical responses, whilst the electrical energy harvesting ability and heat wave propagation in orthotropic piezoelectric plate are maximally lifted.</p>