Liao River Estuary in Northeast China is one of the most important seven estuaries in China. Grain size, clay minerals, major and trace elements and rare earth element (REE) compositions were employed to evaluate the chemical weathering and climate of provenance area, and source-rock composition, and to further infer the provenance and tectonic setting of the Liao River Estuary sediments. Except for the SiO₂, K₂O and Na₂O contents, the contents of all the major element oxides in the sediments were positively correlated with the Al₂O₃ contents, suggesting that they were associated with clay minerals/micaceous in the sediments. The chemical index of alteration (CIA) ranged between 56 and 64 with an average of 61 in the sediment samples reflecting low to intermediate weathering intensity of source area. The ratios of smectite/kaolinite, smectite/(illite+ chlorite) and Rb/Sr were higher during 1963–2003, indicating that the weathering was enhanced and the regional climate was relatively warm and humid. The geochemical indicators suggested that granite was the most likely source rock for the sediment samples. The La–Th–Sc, Th–Co–Zr/10 and Th–Sc–Zr/10 diagrams suggested that the provenance of the sediments was evolved from continental island arc setting. Moreover, the source rock characteristics and tectonic setting were consistent with those in the eastern of Inner Mongolia Autonomous Region. It was concluded that the source area was mainly located in the east of the Inner Mongolia Autonomous Region.