This thesis evaluates the correlation between tissue injury (the ablation site depth) and its predictor (voltage change Va-b), and introduces a newly-developed feedback control system that may help to reduce the incidence of tissue thermal injury. Tissue thermal injury can have some severe consequences, however, there is currently no effective way to prevent its occurrence. Ablation tests were performed by using an impedance bridge circuit and an ablation test model, which had been introduced by Robert and Liang in their studies, respectively. The ablation site depth was measured using a laser displacement measurement device. The feedback control system was developed based on LabVIEW and Arduino programs. When the voltage change exceeds the predefined value, the feedback control system can stop further ablation operation. Both the voltage change and the ablation site depth were found to increase as the delivered heat energy increased. The correlation between the ablation site depth and voltage change was moderate when ablation tests with middle or long duration were performed (R2 = 0.49 and R2 = 0.55, respectively). It was found that the depth moderately correlated to the voltage change when ablation was performed with a proper duration (2 to 3.5 seconds), and that the newly-developed system reduced, to some extent, the incidence of tissue thermal injury.