Construction set block

The invention discloses a toy building element. The toy building element comprises an element body and two first connecting pieces, wherein the element body comprises a first connecting arm, a second connecting arm and a third connecting arm which are integrally formed; the first connecting arm and the third connecting arm are oppositely arranged in parallel, and are perpendicular to the second connecting arm; each first connecting piece comprises a left side plate, a right side plate, a rear side plate, a bottom plate and a top plate; one first connecting piece is arranged on the first connecting arm, and the outer surface of the top plate of the first connecting piece is flush with the inner surface of the first connecting arm; the bottom plate of the other first connecting piece is arranged on the second connecting arm; the left side plate, the right side plate, the rear side plate, the bottom plate and the top plate are matched to form a containing groove, and an opening is formed in one face, opposite to the rear side plate, of the containing groove; each containing groove comprises a plate groove and a column groove; the column groove is provided with limiting clamping bulges or limiting clamping grooves matched with each other. The toy building element is matched with another toy building element through the two first connecting pieces, so that the connection of the two toy building elements is realized, and the assembly is convenient.