The growth law of tin whiskers on the surface of the oxidized CeSn3, LaSn3, (La0.4Ce0.6)Sn3 and ErSn3 precipitates was investigated during the aging. The results indicate that during aging at room temperature, rapid tin whisker growth was found on all of the oxidized RE-Sn surfaces, hillocks and kinked whiskers were easily formed on the oxidized LaSn3 surface, needle-like and kinked whiskers were easily formed on the oxidized CeSn3 and (La0.4Ce0.6)Sn3 surfaces, especially, large sized rod-like and stick-like whiskers were easily formed on the surface of the oxidized ErSn3 phase. During aging at 150 ℃, no whiskers were found on the surfaces of the oxidized CeSn3, LaSn3, (La0.4Ce0.6)Sn3 phases. However, a great number of thread-like whiskers were formed over the whole surface of the oxidized ErSn3 phase. In conclusion, the oxidation tendency of RE-Sn phases dominates the growth law of whisker on the oxidized RE-Sn surface