Abstract Background, Aims and Scope. Wetland soil is one of the largest natural contributors to methane emissions, which is a prevalent greenhouse gas. The vertical flux pattern of methane in soils is unclear. To investigate the relationship between methane vertical flux, soil total organic carbon (TOC) and methanogen, we were monitored in the riparian buffer of a wetland park from August 2018 to January 2020. The objectives of this study were to (1) analyze the vertical variation in methane fluxes within the riparian buffer and (2) investigate the vertical space relationships between methane fluxes, TOC and methanogens. Furthermore, the results of this study could provide better information for understanding the vertical linkage between methane, TOC and methanogens. Methods. The study area is the Living Water Garden (LWG), a wetland park in Chengdu, Sichuan Province, western China (30◦40’ N, 104◦05’ E), which is a city park using a constructed wetland system (CW) to treat polluted water from the Jin River. The sampling site is close to the park inlet, located on the bank of the Jin River, a flat riparian buffer with an area of about 100 m2 (Fig. 1c, the red dashed box). Methane flux was measured once per month (in mid-month) using a portable greenhouse gas flux measurement system (WS-L1820, WEST Ltd., Italy). The sampling frequency is one time on a selected day and the sampling time was between 11:00 am and 12:00 am. There are 6 selected monitoring sites with 4 monitoring depths including surface, 5cm, 10cm and 15cm. Soil sampling and methane flux measurements are performed on the same days. After methane flux monitoring, soil samples were collected. Soil sampling sites were also same as the methane monitoring sites. At each sampling site, soil samples were excavated at depths of 0-5 cm, 5-10 cm and 10-15 cm. Gene copies of the methanogens (mcrA) were determined by q-PCR on the ABI 9700 Real-Time PCR system. Sequencing data was processed using the quantitative insights into the microbial ecology (QIIME) pipeline. SPSS software (version 21, SPSS Inc., USA) and the software package R (R Foundation for Statistical Computing, Austria) were used for statistical analyses and data graphing. Structural equation model (SEM) was conducted using the AMOS statistical software (version 21, IBM SPSS, USA). Results. During the study period, the average surface methane emission was 81.86 mg m-2 h-1 and ranged from 20.42 mg m-2 h-1 to 190.75 mg m-2 h-1. Cumulative methane emissions from studied area was 7.26 kg CO2eq m−2 year−1 and the global warming potential (GWP) was at a moderate level. The results reveal that the Methanobacteriaceae, Methanosarcinaceae and Methanoregulaceae were the major methanogenic microorganisms in the study area. The mathematical regression of methane flux (z, mg m-2 h-1) with soil depth (x, cm) and TOC (y, g kg-1) was as follows: z = 52860.66 + 54.44x - 2.96x2 - 26788.64y + 4487.80y2 - 249.34y3 (R2=0.82). It indicates that the relatio