The utility model relates to an adjustable frame of doors and windows of buildings which can adjust and assemble according to the size of wall holes, aimed at providing the window frame of a door frame which has the advantages of simple structure and convenient installation. The frame of the doors and windows forms an n shape by edge frames 1, 2, 3, and the edge frames are connected with the outer slat 4 and the inner slat 5 of an L-shaped section through an adjustable connecting structure 9 to form the n-shaped section of a clamp wall 6. The combining part of the outer slat and the inner slat is embedded with a stop strip 8, and the adjustable connecting structure 9 is provided with wall connecting pieces 12, 15 and a fixing plate 16 which is connected with the wall connecting pieces. The fixing plate is provided with a lateral dovetail groove 17, and the outer slat and the inner slat are provided with dovetail strips 21 matched with the dovetail groove.