Abstract: The effects of grouting were as follows: to eliminate the influence of technological defects; to recover the bearing capacities of strata; and to improve the bearing capacities of piles. To improve the bearing capacity of piles under Sutong Yangtze River Bridge, different post grouting techniques were adopted to large diameter and super-long piles. Self-balanced testing was used to determine bearing capacity and to verify grouting effect. Based on the test results, bearing capacity, settlement and bearing characteristic before and after grouting were analyzed. The research results were applied in the design of piles of Sutong Yangtze River Bridge to solve the difficulty and to achieve the remarkable economic benefit.