The heterogeneous precipitation behavior of η phase at E/Al interfaces in 7475 aluminum alloy has been studied using high resolution transmission electron microscopy (HRTEM) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) electron tomography. It is found that the nucleation location, the nucleation rate, the growth rate and morphology are greatly different when η phase are formed at E particles with different morphology and volume or the same E particle. The decisive factors that affect the nucleation and growth of η phase are the interface energy and elastic strain energy of E phase. The growth of η phase belongs to theSdiffusion-controlled transformation. Solute atoms are transferred by the interphase interface diffusion at a high speed.