The morphological evolution and precipitation kinetics of gamma' phase in Ni-Al alloys with the variation of volume fraction are studied by using phase-field simulation. The variation of morphology, particles number density and coarsening rate constants are quantitatively clarified with increased volume fraction. The shape of gamma' phase changes from square to rectangular and then to connected strip structure, so the average aspect ratio of gamma' phase increases. The change rate of particles number density has an uniformly increase at the nucleation and growth stage, while it increases firstly and then decreases for volume fraction greater than 30% at the coarsening stage. The coarsening rate constants decrease for the volume fraction less than 20%, while increase when the volume fraction is greater than 30%. In addition, the width of the particles size distribution (PSD) broadens and the peak value decreases, the peak position shifts from 1.0 to 0.5, the PSDs deviate from the theoretical value by the Lifshitz-Slyozov-Wagner for the large volume fraction.