Through a two-year follow-up study among 2,845 middle school students, we examined the impact of baseline negative life events (NLE) on follow-up negative copying style (NCS) and Internet addiction (IA), and the mediation of NCS between NLE and IA. We found that all NLE, NCS, and IA were correlated, and that both NLE and NCS were risk factors for IA. Structural equation modeling (SEM) results showed that NLE were associated with increased NCS (β = 0.17, p < 0.01) and IA (β = 0.16, p < 0.01), that NCS was associated IA ( β = 0.33, p < 0 0.01), and that NCS partially mediated the effect of NLE on IA ( β = 0.17, p < 0.01). This large longitudinal study provided solid empirical evidence that NLE and NCS played important roles in IA among middle school students. Educators and policy makers may adopt corresponding approaches to address IA among this population.