The emission levels and profiles of unintentionally formed polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) were comprehensively investigated in flue gases released from 16 regenerative thermal oxidizers (RTOs) belonging to 8 pharmaceutical industries (PIs) in China. The PCDD/F total concentrations and TEQ values with great variation, ranged from 0.148–9.051 ng m–3 and 0.008–0.255 ng I-TEQ m–3, respectively. Emission levels of most RTOs were lower than the emission standard of China (0.1 ng I-TEQ m–3), yet two were above 0.25 ng I-TEQ m–3. The PCDD/F concentrations in flue gases were in the order of HWIs > MSWIs > PIs. OCDD was identified to be the dominant congener in most RTOs, accounting for 21–71 wt%. In addition, 1,2,3,7,8-PeCDF, 2,3,4,7,8-PeCDF and 1,2,3,4,7,8-HxCDF were effective TEQ indicators, especially for 2,3,4,7,8-PeCDF with a Pearson correlation coefficient of 0.995. The estimated annual emission amount (AE) of PCDD/Fs for PIs in this study was in the range of 0.435–11.016 mg I-TEQ year–1, with an average of 2.65 mg I-TEQ year–1. It was estimated that 19.96 g I-TEQ of PCDD/Fs were emitted from Chinese PIs to atmosphere in 2017. This is the first comprehensive investigation on the unintentional emissions of PCDD/Fs from PIs in China.