Abstract: The simultaneous measurement of multiple thermal parameters of living tissues is of great significance for medical clinical applications. A parameter estimation method using improved genetic algorithm (GA) was proposed to simultaneously estimate the multiple thermal parameters of living tissues. In the method the real-coded GA was designed, the selection, crossover and mutation operators were improved, and the niche mechanism was applied to improve the capability of global optimization. The simulation and experimental researches of a dynamic phantom and a human forearm indicate that it is feasible and effective to simultaneously estimate the multiple thermal parameters of living tissues with high accuracy by the proposed method.