The contents and mineral and chemical compositions of the SPM in the Changjiang River were determined on the samples collected from 25 hydrological stations in the mainstem and 13 hydrological stations in the major tributaries during 2003～2007. Based on these data, the spacial and temporal variations of mineral and chemical compositions in Changjiang SPM, and their geological and environmental implications were systematically investigated. The samples collected in this study have an average SPM content of 256.5mg/L, which is moderate in the world large rivers. Large spacial and temporal variations of SPM contents are observed in the Changjiang River, corresponding to the changes of flow speed, runoff and SPM supply, which are effected by the factors, such as the slope of the river bed, local precipitation, weathering intensity, erosion conditions and anthropogenic activities. The SPM contents in the Changjiang River reduce gradually in recent years, reflecting the effects of tree planting and dam-building in its upper reaches. Especially in the Three Gorge Reservoir prominent sedimentation causes significant reduction of SPM contents, which leads to increase of embankment washout in its lower section, reduction of sedimentation in the Dongting Lake and Poyang Lake, as well as in the estuary area. The environmental effects of these changes will be very significant and should be evaluated and treated carefully. The SPM of the Changjiang River consists of clay minerals, clastic silicate and carbonate minerals, some heavy minerals, iron hydroxide and organic compounds. A comparison between the mineral composition of SPM in the Changjiang River and that in the Yellow River indicates that the chemical weathering activity in the Changjiang River area is much more intensive than in the Yellow River area, and the physical weathering activity in the Changjiang River area is less intensive than in the Yellow River area. From upper reaches to lower leaches, the contents of clay and clastic silicate in the Changjiang River SPM increase gradually, but the content of carbonate minerals decrease gradually, corresponding to the wetter and hotter climate and more intensive chemical weathering in the middle and lower reaches. In comparison with the upper crust rocks, the SPM in the Changjiang River has lower contents of SiO2、CaO、K2O and Na2O and higher contents of TFe2O3, reflecting preferential loss of Si、Ca、K and Na and enrichment of Fe in chemical weathering processes of silicates. In comparison with the world river and the Yellow River, the SPM of the Changjiang River shows higher contents of SiO2 and Na2O, indicating its higher intensity of chemical weathering. Compared with the sediments of the river beds, the Changjiang River SPM has lower contents of SiO2 and Na2O, and higher contents of Al2O3、K2O 、MgO and TFe2O3, reflecting the enrichment of the smaller particles of clay and iron hydroxide in SPM. From the upper reaches to lower reaches, the CaO and MgO contents in SPM decrease gradually, but the content of SiO2 increase gradually, corresponding to the increase of clay minerals and decrease of the carbonates. The Co、Ni、Cu、Zn、Pb and Cd contents in the Changjiang River SPM are all higher than those of the upper crust rocks, which may be caused by their preferential adsorption by clay mineral in weathering processes. High Cu, Pb and Zn contents in SPM of Panzhihua, Yibin, Jiujiang, Datong and Nanjing stations may be related to the local mining activities. Remarkable high Cd anomalies are found in the Fushun and Changsha stations during July 2005. Campared with the bed sediments, the Cu、Zn、Pb and Cd contents in the Changjiang River SPM are several times to several tens of times higher, probably reflecting more intense mining activities in recent years, which should be considered in evaluation of the long term environmental variation of the drainage area. The total REE contents in SPM of the Changjiang River are slightly higher than that of the average world shale. The REE distribution pattern of Changjiang River SPM is similar to that of upper crust, indicating that the rocks exposed in the Changjiang River basin have similar chemical compositions with average crust rocks, and no obvious fractionation on REE has appeared in the weathering process.