Abstract: In order to research the foundation bearing capacity changes of silty sand geological condition under the condition of water level change effect, the author does the site experiment on Jinan Jianbang Yellow River Road Bridge Project. By choosing the location, collecting and analyzing data, the author gets the conclusion that when the beach 0~2.0 m above the phreatic line, as the phreatic line has decreased, its foundation bearing capacity will keep the linear growth state, when more than 2.0 m above the phreatic line, the foundation bearing capacity will tend to be stable.