As an indemnificatory public rental housing project, the apartments will be the first homes for many young people in this coastal city, which meets the diversified living needs of new citizens as much as possible. The design challenge is to provide prefabricated, changeable and multifunctional space in a standard unit of 40 square meters. From the perspective of future users, the fabricated steel structure building provides the best base for this 40 square meter unit. It is transparent and square, column free and wall free, which can accommodate a variety of lifestyles and residential structur