OBJECTIVE To evaluate the economics of pertuzumab combined with trastuzumab and docetaxel（PTD）regimenversus trastuzumab combined with docetaxel（TD）regimen in first-line treatment of human epidermal growth factor receptor 2 （HER2）-positive metastatic breast cancer. METHODS From the perspective of Chinese healthcare system，the partitioned survivalmodel was constructed by using survival data disclosed in the CLEOPATRA clinical trial and relevant literature data. The time horizon of the model was set as 20 years and the cycle length of the model was 3 weeks，and discount rate was 5％. The output indicators of the model included the cost and quality-adjusted life years（QALYs）of the two treatment regimens. The reshold of willingness-to-pay（WTP）was set as 1-3 times per capita gross domestic product（GDP）in China in 2020，i. e. 72 000-216 000 yuan/QALY. One-way sensitivity analysis and probabilistic sensitivity nalysis were used to evaluate the influence of model parameter changes on the robustness of the results. RESULTS The results of base-case analysis showed that within the horizon of 20 years，PTD regimen could bring more health benefit than TD regimen（3.28 QALYs vs. 2.50 QALYs），but the total costs was higher（1 219 376.83 yuan vs. 784 007.84 yuan）. Compared with TD regimen，the incremental cost-effectiveness ratio of PTD regimen was 554 625.46 yuan/QALY，which exceeded threshold of WTP. The results of one-way nsitivity analysis showed that the utility of progression-free survival state hadthe greatest impact on the results；the results of probability sensitivity analysis showed that the probability of PTD regimen considered as to be cost-effective was 1％ when using the 3 times per capita GDP in China in 2020 as the threshold of WTP；when the threshold of WTP increased to 550 000 yuan/QALY，the probability of PTD regimen considered as to be cost-effective would reach to 50％. CONCLUSIONS Compared with TD regimen，PTD regimen is unlikely to be cost-effective in first-line treatment of HER2-positive metastatic breast cancer.