Background: Impower133 and CASPIAN studies showed that PD-L1 antibody combined with first-line chemotherapy could prolong the overall survival. Our previous study showed that nab-paclitaxel had a promising efficacy as later line setting in ES-SCLC. This phase II trial aimed to evaluate the efficacy and safety of camrelizumab plus nab-paclitaxel and carboplatin as front-line setting in ES-SCLC. Methods: Key inclusion factors were18-75 years old, histologically or cytologically confirmed ES-SCLC, ECOG performance status 0-1, no previous systematic treatment. Patients (pts) received 4 ̃ 6 cycles of camrelizumab (200mg, D1, q3w) combined with nab-paclitaxel (230mg/kg, D1, q3w) plus carboplatin (AUC = 5, D1, q3w), then camrelizumab maintenance until disease progression or intolerable side effects. The primary endpoint was 6 months progression free survival rate. Secondary endpoints included PFS, ORR and safety. Results: From April 2021 to December 2021, 36 pts who received at least one dose of camrelizumab were included into this report. The median age was 60.5 (range: 32-73) with 30 (83.3%) males, 19 (52.8%) former smokers, and 36 (100%) ECOG performance status 1. The median drug exposure was 5 cycles, and 18 (50%) pts entered the maintenance stage. 33 pts had at least one 1 post-treatment tumor assessment. Among them, 32 partial responses (5 unconfirmed), 1 progressive disease (new lesion). The confirmed ORR was 81.8% (27/33), the unconfirmed ORR was 97% (32/33), DCR was 97% (32/33). The median PFS was 7.27 months (95% CI: 4.7 – 9.8 months). 24 (66.7%) pts had at least one adverse event, and 10 (27.8%) pts experienced grade 3 or 4 adverse events, including 10 (27.8%) neutropenia, 4 (11.1%) leukopenia, 2 (5.6%) thrombocytopenia, 2 (5.6%) anemia, 2 (5.6%) hepatic function abnormal,1(2.8%) alanine aminotransferase increased, 1(2.8%) hyperglycaemia, 1(2.8%) diabetes mellitus, and no grade 5 adverse event happened. Conclusions: Camrelizumab plus nab-paclitaxel and carboplatin had promising efficacy and safety profile as first-line setting in ES-SCLC, further validation is warranted. Clinical trial information: NCT04790539.