The Circular Electron Positron Collider is a proposed electron positron collider by the Chinese high energy physics community in 2012, the circular electron positron collider (CEPC) has got warm responses from the international community. This machine could be later upgraded to a high energy proton-proton collider with physics potential far beyond the Higgs factory. The low Higgs mass of ~125 GeV makes possible a Circular Electron Positron Collider (CEPC) as a Higgs Factory, which has the advantage of higher luminosity to cost ratio and the potential to be upgraded to a proton-proton collider to reach unprecedented high energy and discover New Physics. The underground particle-smashing ring aims to be at least twice the size of the globe's current leading collider - the Large Hadron Collid