The present invention provides a foldable projection screen, which comprises: a first housing capable of being folded for engagement and capable of standing while being unfolded; and a projection screen having its two sides respectively fastened on two sides of the first housing so as to be folded and accommodated in the first housing. With the mentioned structure, the foldable projection screen has advantages of small in volume, light in weight, and easy to be carried around, and applicable in a mini-sized or small projector.