Water samples were obtained in the Three Gorges Reservoir (TGR) and Fuling to Jiangyin reaches of the Yangtze (Changjiang) River from April 2006 to March 2007 after the TGR filling, in order to explore the reservoir influence on silica transport in the Yangtze River. The results reveal that the TGR would affect the silica delivery from the Yangtze River. In April and September-October, the dissolved silicate (DSi) concentration decreases along the reservoir due to the retention by the man-made lake, and increases in downstream reaches of the TGD due to the contributions from tributaries in the middle Yangtze River. The TGR trapped approximately 3%-6% DSi in 2006. The huge reservoir tends to remove DSi from the water column during the period between April and December; while it would add DSi from January to March. Biogenic silica (BSi) accounted for 2%-5% of total reactive silica in the Yangtze River. The diatom production plays a minor role in controlling BSi level in the Yangtze River. The retention of DSi loading in downstream reaches of the TGD was observed after impoundment, which would be concerned in the future.