Cloud 9 is an exploration of the three-dimensional city. It blurs the boundary between the ground and the building with the shape interwoven, reshapes the urban landscape. Through the design method of lifting and undulating, the facade along the street makes the internal and external space blend with each other. The continuous undulations and set-back models on the roof connect the sky garden and courtyard. The penetration of the volume improves the micro-climate environment of the building, and adds vegetation to make the Cloud 9 look like a mountain floating in the air.