Jair Bolsonaro，a representative of the far right，became president of Brazil in 2019，and Brazil’s foreign policy began to adjust. Since its establishment in 1991，Mercosur has always been the core of Brazil’s regional strategy and the platform to enhance its international voice. Bolsonaro gave up the South-South cooperation keynote centered on the cooperation of Mercosur in the foreign policy of the labor party government in the past decade. Brazil reemphasized the connection with the United States and other developed countries，and actively used Mercosur to deepen economic and trade cooperation with the EU and made substantive breakthroughs. However，with the new president of Argentina，Alberto Fernández，Bolsonaro made ideological demarcation and repeatedly expressed to withdraw from Mercosur，which made the development direction of Mercosur full of uncertainty. Although there may be short-term fluctuations，in a multipolar world，Brazil’s multilateral diplomatic tradition will not be affected.