In order to further investigate the physical properties of the laser-induced plasma and improve the measurement precision and reliability of the laser-induced breakdown spectroscopy (LIBS) technology, the time evolution process of the laser-induced plasma is studied experimentally. Through fast imaging of the laser-induced aluminum alloy plasma using the ICCD camera, it is found that the lifetime of the laser-induced aluminum alloy plasma is about 30 μs, the plasma has an obvious hierarchical structure, and furthermore the areas and temperatures of different regions present different characteristics during the time evolution process. The time evolution process laws of the electron temperature and the electron number density are obtained using the Boltzmann plot method and Stark broadening of line, respectively. The results show that the electron excitation temperature of the plasma ranges from 6000 K to 9000 K, and it decreases rapidly in the first 3 μs. Besides the electron number density is in the order of 1017 cm-3, it decreases slowly with ICCD detection delay time. The time evolution laws of electron temperature and the electron number density are in agreement with that of the fast imaging by the ICCD camera.