The sofa bed features two usage modes: sofa and bed. When used as a sofa in daily life, the backrest is angled and the seat depth is moderate, allowing for seating or semi-reclining rest. When it needs to be converted into a bed, the bottom frame is pulled out, the back of the sofa seat is raised, and the backrest is flattened to complete the unfolding process. The bed surface is a flat rectangular plane, suitable for sleeping. After folding, it occupies less floor space and is suitable for placement in rooms that require flexible use functions.