Decomposition and transformation of input straw in four types of paddy soils were investigated under incubation at 25℃ and 45% water holding capacity (WHC) for 180 d. The soils were derived from different parent materials (weathered granite, quaternary red clay, weathered shale, and river alluvial) in subtropical China, and the adjacent upland soils were selected as a control. During the 180 d period, the mineralization ratios of input straw in the selected paddy soils (18%-21%) were lower than those in the corresponding upland soils (21%-28%). The priming effects of straw amendment on native soil organic carbon mineralization were also lower in the paddy (5%-37%) than in the corresponding upland soils (23%-65%). The decomposed products of input straw were mainly distributed in particulate organic carbon (POC, 9%-21%) and Fe/Al-bound organic carbon (Fe/Al-OC, 12%-24%), followed by humus carbon (HMC) (11%-15%), whereas only a small part was distributed as microbial biomass carbon (MBC, 2%-7%) and dissolved organic carbon (DOC, 0.1%-0.7%). In paddy soils, the conversion ratios of input straw in POC, Fe/Al-OC, and MBC (15%-21%, 17%-24%, and 6%-7%) were higher than those in upland soils (9%-17%, 13%-18%, and 2%-4%). In addition, the 2,000-250 μm coarse water-stable aggregates in paddy soils tended to receive more decomposed products of input straw than those in upland soils (10%-13% vs. 6%-7%), whereas no significant difference was observed between paddy and upland soils in other small sizes of aggregates. The results indicated that the mineralization of input straw may be lower in paddy than in upland soils derived from different parent materials, possibly owing to stronger physical protection in soil coarse aggregates, chemical protection by binding with Fe/Al oxyhydrates, and larger transformation to stable fractions of input straw during its decomposition in paddy soils. This fate of input straw decomposition may contribute to a higher organic carbon accumulation in paddy than in upland soils.