Abstract: Based on excavation of foundation pit for a sluice in Zhejiang Province, field tests on deformation characteristics of retaining structure with non-equal-length double-row piles are performed by burying inclinometers and reinforcement stress meters in row piles. The influences of the mounted depth of back row piles are discussed by using the elastic foundation beam method. The results indicated that: the change laws of top displacement, pile shear and bending moment of double piles are consistent with those of equal-length double-row piles. With the increase of the embedded depth of back row piles, the top horizontal displacement of front and back row piles decreases. The shear force and bending moment of front row piles decrease, while those of back row piles increase. When the embedded depth is more than 3/4 of the pile length, the decrease or increase trend of top horizontal displacement, shear force and bending moment of piles are not obvious. These achievements may provide certain reference for the design optimization of supporting structures for foundation pits with double-row piles.