With a tradition of compact development, green network within developed urban area of Hong Kong seriously suffers from loss of habitats and disconnection. Fortunately, most Affordable Housing (AH) projects in this city provide certain proportion of site areas for open space and contribute a lot to urban green network. Their environmental and social benefits are discussed at city, district, and class levels in this chapter. Taking Sham Shui Po District, one of the earliest settlement of human society and densely developed area as an example, its green network was analyzed with ArcMap. Besides, a virtual extreme scenario with all the AH projects replaced by conventional private developments is compared with the status quo with ArcMap and FRAGSTATS. It is found that current greeneries provided by AH projects play an important role in green network of this district. They are not only contributive to urban ecosystem, but also very supportive to citizens’ daily life. Taking this as reference, it is critical for the local government to plan AH developments thoughtfully so as to ensure a well configured urban green network under the compact development mode.