The effect of the elastic energy on the morphology and orientation of g ′ particles and the coalescence behavior of multi-particle were studied based on the three-dimensional phase-field method, and the influence of precipitate volume fraction on the number, average size and size distribution of g ′ particles were also studied. The results show that the g ′ particle is cubic under elastic energy, aligned along the <100> elastic soft directions. The effect of the elastic energy on the coalescence behavior of multi-particle mainly depends on the elastic interaction which is related to the particles' distribution, size and the distance of domain boundary. With the increase of precipitate volume fraction, the number of g ′ particles first increases to the maximum and then reduces; meanwhile the average size increases gradually.