Abstract: The growth behavior of tin whisker on tin coating with thicknesses of 3 μm, 5 μm and 13 μm was investigated after thermal aged at 70℃ for 24 hours and then placed at room temperature for 60 days. The tin coating with thickness of 3 μm was selected to perform the external loading experiments with Dynamic Mechanical Analyzer (DMA Q800, TA-Instruments). The experimental results show that the tin whisker grew much easier on thinner coating than on thicker one under the same thermal aging condition. Moreover, external compressive load led to much more and faster tin whiskers growth on thin coating with thickness 3 μm, compared to tensile load.