This study analyzes the relationship between the age of first migration and the probability of repeat migration focusing on rural to urban migrants in China. It is based on the data of the 2015 Migrant Dynamics Monitoring Survey (MDMS). The data shows that 52.64% of migrants had experienced repeat migration before 2015, the amount of which is huge. The empirical results indicate an inverted U-shaped connection between age of first migration and the probability of repeat migration. The probability of making repeat migration from rural to urban areas reaches its peak if an individual experienced his/her first migration at around 16 years old. The probability for repeat migration continues to increase before the age of 16 and keeps dropping afterward. Additionally, this study explores the reason for this inverse U-shaped relationship, and it finds that reasons for first migration have great impacts. Specifically, the probability of repeat migration goes up with age if an individual first migrates before age 16 and is accompanied by parents. This probability decreases with age, if an individual first migrates after or at age 16, because of work.