In order to study the optimal row spacing and supporting structure internal forces of the double-row piles supporting structure of deep foundation pit, indoor model tests were carried out for double-row piles supporting structure with row spacing of 2D, 3D, 4D and 5D (D is the diameter of the pile), respectively. Jacking forces were applied to simulate the load of different excavation depths, and the stress in the pile and the displacements at the top of the piles were measured. The effects of row spacing and excavation depth on bending moment and the displacement of these two rows of piles in the double-row piles supporting system were analyzed, and the optimal row spacing was obtained. This research shows that the change of row spacing causes large influences on both the bending moment of the pile and the displacements at the top of the pile. The change of row spacing affects the internal stress of the back pile much more than that of the front pile. It affects the positive bending moment more than the negative bending moment. The curve of depth-displacement is approximately a quadratic function curve passing the origin. It is positive bending moment in the pile above the foundation pit, and it is negative bending moment in the pile below the foundation pit. The displacement at the top of the pile reaches the smallest value when the row spacing is 3D, and the positive bending moment reaches the maximum value when the row spacing is 4D.