The invention discloses a neck type retaining block which comprises a front surface, a rear surface, a top surface, a bottom surface, a left side and a right side, wherein, the middle of the top surface is provided with a cavity throughout the top surface and the bottom surface; the top surface at the front side of the cavity is also provided with a horizontal convex prism; the bottom surface below the convex prism is provided with a groove matching with the convex prism; the top surface and the bottom surface of the rear side of the convex prism and the groove are respectively provided with a arc embossment and a groove; and the right and the left sides are provided with two vertical concave grooves symmetrically, when construing retaining walls, the arc embossment and the concave groove at the upper and lower retaining walls are matched with each other for fixing reinforcing materials, the space left by the splicing of the vertical grooves on two adjacent retaining blocks of the same floor is arranged above the upper cavity of the lower retaining block, so as to form a space for filling gravels and soils. The retaining block is provided with the matching embossment and concave groove to prevent the reinforced materials between retaining blocks from abrasion and damage, and at the same time, the upper and the lower retaining blocks are connected with each other in a clamping form, thus improving the construction speed.