With improved Hungate anaerobic technique, the amounts of methane—producing bacteria (MPB) in the submerged paddy soil planting rice crop were determined by the MPN (The Most Probable Number) method and the rolll tube method at the same time. The esults obtained showed that the amounts of MPB during different growing periods of rice were significantly different, the amount of MPB grown on mixed substrate was the highest at the late tillering stage of early rice, up to 3.6×10¹⁰/g dry soil; that on H₂/CO₂ increased significantly at the vigorously tillering stage of late rice, reaching 3.1×10¹¹/g dry soil at milk ripening stage; the amounts of MPB grown on formate and acetate were higher, about 3.7×10⁸/g dry soil and 1.2×10⁸/g dry soil respectively at the vigorously tillering stage of late rice; and that of MPB grown on methanol-had no significant difference during the different growing periods being, about 3.5×10⁵/g dry soil. The amounts of MPB had no marked diffea-ence in soil at different depths.