In June 2016，the UK's referendum on its EU membership resulted in a “no”vote. On March 29 2017 the UK government handed to the EU its official letter triggering Article 50 of Lisbon Treaty，thus commencing the historic Bexit negotiations. The first round of negotiations between the EU and the UK was launched on June 19，2017. After six months of hard talks with twists and turns and despite the remaining divergences over certain crucial issues，a deal was declared to have been reached between the UK and EU in December 2017，which ended the first round of talks and opened the door to move to the next phase. Brexit has brought about far-reaching impacts on both the domestic politics and external policies of the UK. In the domestic arena，the early parliamentary elections in June 2017，which could be attributed in a large part to Brexit，have significant consequences for the party systems of the UK. In addition，the political and social divisions have been further sharpened. In the international arena，the UK endeavours to construct a “Global Britain” and rebuild its diplomatic ideas and policies.