Antiretroviral therapy has significantly expanded and an increased proportion of patients have switched to second-line regimens in China. We describe the outcomes of second-line therapy among patients having received long-term first-line ART. A prospective follow-up study was conducted in rural areas in China. We compared the virological, immunological outcomes and genotypic drug resistance (DR) profiles before and after regimen switches. A total of 303 patients were enrolled, 283 (93.4%) were retained at 12 months. Of 90 participants with HIV-RNA ≥ 1000 copies/ml before switch, the proportion of viral load (VL) ≥ 1000 copies/ml at 6 and 12 months was 49.4% and 43.9%, respectively. Of 213 patients with HIV-RNA < 1000 copies/ml before switch, the proportion of VL ≥ 1000 copies/ml at 6 and 12 months was 4.8% and 6.5%, respectively. The rates of drug resistance to NNRTIs, NRTIs, PIs decreased from 65.5%, 53.3%, and 1.1% before regimen switch to 26.8%, 18.3%, and 0% at 12 months, respectively. DDI-based initial ART regimens and missing doses in past month were associated with HIV RNA ≥ 1000 copies/ml at 12 months. The results showed that patients having received long-term first-line ART and experiencing virological failure had good virological outcomes after switching to second-line treatment in China.