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Wastewater treatment plants (WWTPs) contribute increasing amounts of greenhouse gases (GHGs), due to rapid development and increasingly stringent wastewater discharge limits in China. In this study, GHG emissions from 38 WWTPs in Beijing were estimated using the pollutants parameter normalizing method (PPNM) and the effects of various factors were analyzed. The result showed that, the total GHG emissions of Beijing WWTPs in 2017 were 1 045 661.5 t CO 2 -eq (tons of CO 2 -equivalent), the direct and indirect emissions were 186 366.0 and 859 295.5 t CO 2 -eq, respectively. The average emission intensity was 0.603 kg CO 2 -eq/m3. Direct and indirect GHG emissions were influenced by various factors, such as treatment process, influent parameters and treatment scale. The anaerobic-anoxic-oxic (AAO) process demonstrated low emission intensities (0.092 kg CO 2 /m3), while biofilm processes (MBBR) obtained relatively high emission intensities (0.277 kg CO 2 /m3). Direct GHG emission has a positive correlation with the amount of pollutant removed and low influent pollutant concentrations (chemical oxygen demand [COD]<300 mg/L and total nitrogen [TN] <20 mg/L) can lead to high indirect GHG emission intensities. The low power utilization efficiency of small-scale WWTPs (<1 × 107 t/a; 6.60 kWh/kg COD; 30.54 kWh/kg TN) contributed to additional GHG emissions. Compared with the GHG emissions in Shanghai in 2016, higher influent pollutant concentrations and stricter discharge limits contributed to higher GHG emission intensity in Beijing for both direct (0.108 kg CO 2 /m3) and indirect (0.496 kg CO 2 /m3) emissions. The comparison results between cities indicated that the PPNM method achieved a more accurate account of GHG emissions, and the analysis results provided support for carbon emission reduction. [Display omitted] • Greenhouse gas emissions from wastewater treatment were estimated for Beijing. • Indirect greenhouse gas emission (859 295.5 tCO 2 -eq) was 4.6 times of direct emission (186 366.0 tCO 2 -eq). • AAO and MBBR are processes with lowest and highest emission intensities. • Strict discharge limits lead to high greenhouse gas emissions. [ABSTRACT FROM AUTHOR]