The purpose of this essay is to critically discuss sustainable urban development on Brownfield sites in United Kingdom. It will start with description of background of Brownfield. Then, it will move on to introduce how the issue of sustainable brownfield regeneration is addressed in the UK. The overview of sustainable brownfield redevelopment in UK will be presented, followed by analyzing the example of Connaught square in this part. After that, it will take Hafen city to be the case study. It will examine the strategies about economic, social and environment sustainability; discuss how to transfer these ideas into reality. Finally, this paper will close with gives some recommendations on brownfiled redevelopment in UK.