OBJECTIVE：To evaluate the economics of atezolizumab combined with stardard chemotherapy regimens versus chemotherapy regimens alone as first-line treatment for extensive-stage small-cell lung cancer （ES-SCLC）from the healthcare system perspective. METHODS ：A partitioned survival model was constructed using published phase Ⅲ clinical trial data （IMpower133）and literature data to evaluate the economics of atezolizumaba combined with standard chemotherapy regimens versus chemotherapy regimens alone as first-line treatment for ES-SCLC. One-way sensitivity analysis and probabilistic sensitivity analysis were used to evaluate the stability of the results. RESULTS ：The results of cost-utility analysis showed that the cost of atezolizumab combined with chemotherapy group was 489 598.52 yuan，with utility of 0.70 QALYs；the cost of chemotherapy alone group was 126 276.80 yuan，with utility of 0.55 QALYs；the incremental cost-utility ratio （ICUR）between the two groups was 2 361 709.05 yuan/QALY，far exceeding the willingness-to-pay （WTP）in China （3 times of GDP per capita in 2019，212 676 yuan）. One-way sensitivity analysis showed that progression-free utility value of atezolizumab combined with chemotherapy had the greatest impact on the results of cost-utility analysis ；probabilistic sensitivity analysis suggested that the atezolizumab combined with chemotherapy regimen was not economical within the WTP range of 0-500 000 yuan/QALY. CONCLUSIONS ：Atezolizumab combined with chemotherapy regimen has no cost-utility advantage versus chemotherapy alone in the first-line treatment of ES-CLC under the current economic level of China.