Being the first step of foaming, bubble heterogeneous nucleation of aluminum foam has remarkable effects on the final cell structure of aluminum foam. The bubble heterogeneous nucleation of foaming Al-9Si and TiH2 powder compact has been analyzed. The results obtained are given as follows: (1)The remaining TiH2 particles act as the nuclei during heterogeneous nucleation. (2)The nucleation rate increases with the increasing of TiH2 content, the decrease of TiH2 granularity, the elevation of foaming temperature, and the elongation of foaming time. (3) Only about 5‰ bubble nuclei can survive and develop to the final foam cells. (4)The influence of processing parameters on the nucleation rate descends by the following sequence: foaming temperature elevates 20°C, TiH2 granularity decreases from 150μm to 26μm, TiH2 content increases 0.5%wt., and the time for foaming extends 10s.