Three strong earthquakes, which occurred in the Jiuzhaigou county and its adjacent areas in the 20th century, fit to the temporal triplet distribution with period of 40 years. It is predicted that a strong earthquake will occur again in 2018 based on the period with the 1976 Songpan earthquake as the starting point. In fact, the previous period of actual earthquakes in this area is 43 years, one more than 42 years, so the new period should subtract one year, which means the predicted strong earthquake should occur in 2017.