This study was conducted to assess the moisture distribution in a pre-cracked asphalt concrete pavement in a short-term rain event by finite element method via the diffusion process. The asphalt concrete pavement with three different pre-crack lengths was used to investigate. The results show that the moisture distribution zone increases according to the time of the rain event and the pre-crack length of the asphalt concrete pavement. It is highlighted that the proposed model can effectively assess the moisture distribution in a pre-cracked asphalt concrete pavement. Moreover, this study also found that the pre-crack length affected the moisture distribution in the pre-cracked asphalt concrete pavement significantly. The pavement with higher pre-crack length had a higher increasing rate of moisture saturation with time. In the future, further research should be conducted to investigate the moisture distribution in a pre-crack asphalt concrete pavement in terms of different conditions such as material, environment, and traffic load.