This paper offers a novel explanation for divorce risk along the life-course timeline. Utilizing data from the China Family Panel Studies (CFPS) from 2010 to 2020 and employing an instrumental variable model, the study empirically examines the impact of early-life left-behind and migrant experiences on divorce risk, along with their underlying mechanisms. The findings reveal that left-behind experiences significantly increase the divorce risk among adult second-generation migrants, whereas migrant experiences exhibit no statistically significant effect. The conclusions remain robust after a series of rigorous tests, including the construction of a counterfactual framework and the substitution of instrumental variables. Heterogeneity analysis indicates that, compared to high-income, highly educated, and upwardly mobile groups, left-behind experiences only elevate divorce risk among low-income, less-educated individuals and those without upward social mobility. Mechanism analysis demonstrates that, relative to migrant experiences, left-behind experiences significantly reduce trust in others, heighten tendencies toward introversion and risk-taking, and diminish opportunities to learn marital skills from parents, thereby ultimately increasing divorce risk. The paper recommends strengthening family guidance to enhance young parents' sense of parental responsibility and parenting competencies. Concurrently, fiscal transfer payments should be explicitly conditioned on the tangible outcomes of migrant citizenization initiatives. Furthermore, it is imperative to universally implement residency-based household registration systems that guarantee access to locally-provided basic public services. Comprehensive supporting measures encompassing education, healthcare, and housing must be enhanced to facilitate the citizenization process for migrant population.