A foldable bed frame includes pivotally connected bedsteads. A bedstead includes an upper frame and a side leg assembly pivotally connected with the upper frame. A bedstead also includes one or more oblique supports each pivotally connected with the upper frame and slidably and rotatably connected with the side leg assembly. A bedstead further includes a “⊏” shaped lower peripheral support and a plurality of links connecting the lower peripheral support with the upper frame and the side leg assembly. The lower peripheral support can be folded and unfolded along with the upper frame and the side leg assembly.