Abstract: A bottom frame assembly for a baby crib includes pairs of first and second bottom frame rods, and a hub unit that includes stationary and rotary seats. The stationary seat is connected to the first bottom frame rods at diametrically opposite positions of the stationary seat. The rotary seat is mounted rotatably on the stationary seat, and is connected to the second bottom frame rods at diametrically opposite positions of the rotary seat. By adjusting the angular orientation of the rotary seat relative to the stationary seat, the angles formed between adjacent ones of the first and second bottom frame rods can be varied so that the bottom frame assembly can suit the specified length-to-width ratio of the baby crib.