【Objective】The mitigation of methane (CH₄) emission has long been the focus of governments and researchers worldwide. Rice fields are an important source of CH₄ emission, and CH₄ production is the precondition of CH₄ emission. It is mainly produced by acetate fermentation and CO₂/H₂ reduction. Substantial CH₄ emissions are observed from the permanently flooded rice fields, thus leaving a high mitigation potential of emission. However, reports on the seasonal variation of the methanogenic pathway in these rice fields are limited.【Method】Fresh soil samples from four rice growth stages (tillering stage, booting stage, heading stage, and maturity stage) were collected from a permanently flooded rice field in Ziyang City, Sichuan Province, China. The CH₄ production potential (MPP) was observed through anaerobic incubation experiments. Both stable carbon isotope technique and methyl fluoride (CH₃F, 2%) inhibition method were used to quantify the carbon isotopic fractionation factor for the conversion of CO₂to CH₄₍α_(CO2/CH4)), as well as to quantitatively estimate the relative contribution of acetate-dependent methanogenesis (ƒ_acetate).【Result】The addition of CH₃F significantly decreased the CH₄ production, and the MPP reached the highest value at the maturity stage, ranging from 3.22 to 12.71 µg·g^-1·d^-1. The δ¹³C-value of produced CH₄(δ¹³CH₄) varied from -66.83‰ to -59.62‰, which was much more positive than that of produced CH₄ with CH₃Faddition (from -90.83‰ to -82.26‰). The α_(CO2/CH4)reached its maximum and minimum values at tillering and booting stages, respectively, which was between 1.064 and 1.076. The ƒ_acetate(30%-61%) decreased sharply from 54%-61% at the tillering stage to 30%-35% at the booting stage and then increased to 54%-61% at the maturity stage. Further analysis showed that the seasonal variation of MPP was positively correlated with the variation of soil dissolved organic carbon (DOC) content, and the seasonal variation of ƒ_acetate was significantly related to variations of acetate content.【Conclusion】Distinct seasonal variations were observed in both MPP and methanogenic pathways of the permanently flooded rice fields, which was mainly affected by soil DOC content and acetate content, respectively.