Periodically poled lithium niobate is a widely used material for nonlinear optical frequency conversion by means of quasi-phase matching. Herein, the poling process with the temperature varying from 140 °C to 190 °C is studied. The required polarization voltage to inverse spontaneous polarization and domain distribution are highly related to the temperature variation, which is assigned to the coercive field change. The obtained domain duty cycle shows that the reduction of the coercive field benefits the control of the domain motion in both the horizontal and vertical directions. The finite element analysis of the applied electric field reveals that nucleation plays a crucial role in the periodic poling process. This work provides a strategy for the control of the domain duty cycle by reducing the coercive field of LiNbO3 crystals.