A concrete inside interface processing structure for secant pile construction, including secant concrete pile, formed plain concrete pile, rotary jet grouting piles, steel mesh sheet, ribbed steel bar, Y-shaped connecting piece, reinforced concrete pile, and U-shaped connecting piece; drilled holes are arranged at intervals along axis of the formed plain concrete pile; the ribbed steel bar is anchored in each drilled hole; the steel mesh sheet is formed by connecting longitudinal bars and transverse bars, and driven into a soil body between the formed plain concrete piles; the concrete layer is formed by spraying concrete on the steel mesh sheet; the reinforced concrete pile is cast at outside of the formed plain concrete pile, and tangent to the formed plain concrete pile, and interlocked with the rotary jet grouting piles; the rotary jet grouting piles are tangent to the formed plain concrete pile or secant concrete pile.