Embankment filling on weak subgrades is prone to sliding and collapse failures. Positive-negative batter pile combinations were proposed to be installed at the embankment slope toe to constrain lateral deformations, but systematic inquiries into the mechanical characteristics of positive-negative batter pile combinations are still lacking. The mechanical responses of positive-negative batter pile combinations under lateral loads with different pile length ratios (1/2, 2/3, 1, 3/2, and 2/1) were systematically investigated by the finite element software Abaqus, and calculation and verification were conducted by the structural mechanics force method, providing a basis for the design of positive-negative batter pile combinations at the slope toe. The results indicate that: ① Compared with vertical double-row piles, positive-negative batter pile combinations with the same pile length ratio reduce horizontal displacement by approximately 25%, and displacement of pile bodies of rear-row positive batter piles decreases with the increase of lengths of front-row negative batter piles; displacement of rear-row positive batter piles exhibit “rotation around the fixed end + outward movement in the upper-middle section”, and peak values of horizontal displacement appear in the upper-middle section of pile bodies; ② Peak values of bending moments of pile bodies appear in the upper-middle section of pile bodies; bending moments of rear-row positive batter piles and front-row negative batter piles increase with the increase of lengths of front-row negative batter piles; bending failures easily occur in the upper-middle section of pile bodies of positive and negative batter piles, and rear-row positive batter piles experience bending failures earlier than front-row negative batter piles. As the pile length ratio of front-row negative batter piles to rear-row positive batter piles increases, the peak bending moment ratio of negative batter piles to positive batter piles gradually decreases to 1; ③ By comprehensively considering mechanical mechanisms and construction feasibility, lengths of front-row negative batter piles in actual engineering should be greater than lengths of rear-row positive batter piles, so as to reduce horizontal displacement and peak bending moment ratios of rear-row positive batter piles and improve the overall stability of the subgrade.