A trapezoidal locking, buckling and connecting pile wall device comprises a concave trapezoidal head drilling machine and a convex trapezoidal head drilling machine. A plurality of cemented soil concave trapezoidal head piles at the interval of one convex trapezoidal head pile are manufactured; and when the cemented soil strength of the concave trapezoidal head piles on the two sides reaches a certain degree, one concrete convex trapezoidal head pile is manufactured within the interval between every two concave trapezoidal head piles through the convex trapezoidal head pile drilling machine according to a work manner of the above convex trapezoidal head pile drilling machine, and in this way, a pile wall formed in the manner that the plurality of cemented soil concave trapezoidal head piles and the concrete convex trapezoidal head pile between every two concave trapezoidal head piles are subjected to mutual locking, buckling and connecting is formed and used for soil retaining and leakage prevention of a building foundation.