“Mirror first” can be said to be the first step in the decoration of small-sized houses. “First of all, we must visually give people a sense of transparency. We can open up the bedroom, living room and bathroom to form a large space situation. Since the actual space comparison Small, we must try to make up for the visual defects through design, making it visually transparent, such as the wall connected to the living room and bedroom, using large-area glass, glass brick, or mirror to create virtual space effect.