The current study aimed to evaluate the cost-effectiveness of sintilimab versus docetaxel as second-line treatment for patients with advanced or metastatic squamous NSCLC in China.A partitioned survival model was established to track 3-week patients transition and project the health and economic outputs in 15-year horizon of the two competing options among sintilimab and docetaxel. Clinical data were obtained from the ORIENT-3 trial, cost and utility values were gathered from the local charges and published studies. Total costs, life-years (LYs), quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratio (ICER) were evaluated. Sensitivity analyses were conducted to assess the robustness of the model outcomes.Base-case results revealed that sintilimab yield marginal cost of $4,700.53 and additional 0.32 QALYs, resulting in an ICER of $14,615.31 per QALY gained, which lower than the willingness-to-pay (WTP) threshold of $38,224/QALY in China. One-way sensitivity analyses showed that the cost of best supportive care was the main driver of the ICER, and PSA demonstrated that the model outputs were robust.Sintilimab could be considered the cost-effective second-line strategy for patients with advanced or metastatic squamous non-small-cell lung cancer compared with docetaxel in China.