Taking the frame seawall in Wenzhou as an example, the finite element strength reduction method was used to analyze the influence of dense-row piles and filling height of the downstream slope on the deformation and stability of the seawall. The results show that compared to double-row pile cases, the horizontal displacement of the piles near the top of piles in single-row pile cases decreases, the overall stability safety factor of frame seawall decreases substantially. With the increase filling height at the downstream slope, the horizontal displacement of the dense-row piles increases continuously with the maximum increase rate at the top of piles, and the overall stability safety factor of the frame seawall decreases sharply.