It is still an open problem how the thermal effect influences the fracture behavior of piezoelectric materials especially under cycling electrical loading. Experimental observations have found that the fracture toughness of piezoelectric solids under electric loading may be greatly different from that under mechanical loading. A pronounced rise of temperature may be caused either by mechanical or by electric loading. In this paper, the thermal effects and energy dissipation mechanism in cracked piezoelectric materials under cyclic-electric-loading have been studied. The temperature rise is derived under the assumption of decoupling between thermal and electromechanical fields and the influences of frequency and the shape of electric wave on the temperature rise are quantitatively analyzed.