Microstructure quantitatively analysis is significant for building the relationship between microstructure and properties, especially the ageing precipitation kinetics in aluminum alloys. A core parameter (aspect ratio) was introduced to describe the morphology change of precipitation. Aspect ratios of T1-plate precipitates in Al-Cu-Li-Zr alloys, S-plate precipitates in Al-Cu-Mg alloys and β-rod precipitates in Al-Mg-Si alloys were quantitatively analyzed. Results indicated that aspect ratios of precipitates increased at the early stage of ageing, then reached the peak and finally decreased slowly. The soft-impingement theory and HHC theory were introduced to model the ageing kinetics. Thermodynamics and kinetics parameters of different precipitates were also calculated in the model. Simulate results of different precipitates agree well with the experimental results.