Three-dimensional laminar boundary layer over a semi-infinite surface with linearly corrugated cross-section has been solved numerically. The existing solution on semi-infinite corner flow is extended in the present study to include the more complex geometry, the combination of rectangular concave corner and convex corner. An initial plane is introduced near the leading edge where the two corners are yet independent of each other and the existing similarity solutions on the two corners can be matched. Finite-difference solution of the three-dimensional boundary layer equation has produced pictures on downstream propagation of the effect of the two neighboring corners. Streamwise velocity profiles, iso-velocity contours in the boundary layer, the cross-flow velocity vectors and streamwise skin friction are presented at various different stream-direction cross-section, for Raynolds number $1.0\times10^4$.
