The courtyard is located in the Beijing Hutong area with only 12㎡. Mirror glass is used on the ground and walls of the yard. When the owner steps into the door, she will be surrounded by the perspective effect of specular reflection, which increases the permeability of the space and gives people a double landscape experience. The unique reflectivity of the mirror allows the surrounding hutongs, trees, and sky to be reflected on the ground of the yard, which brings more possibilities to space. This kind of interaction between virtual and reality is more prominent. With the continuous changes of reflection and the surrounding environment, the mirrored courtyard shows a rapidly changing beauty, each moment is unique, just like time, cannot be recorded but can only be felt. The "invisible" state reflected by the "tangible" in the courtyard also makes the viewer and the environment, the environment and architecture, architecture, and people all have a kind of eye-to-eye relationship, which hides the boundary of the space. The transparent glass wall adds daylighting to the interior space, allowing the line of sight to penetrate each other on both sides of the courtyard, creating an extroverted and introverted courtyard space.