The  reign of Louis XIV  in  France(1643-1715)  and  of  the Kangxi Emperor in  China(1662-1722)   witnessed  the  first scientific contacts between  the two countries.French  Jesuits were sent   to China  as  missionaries、scientific  ambassadors  of  the King at  the Chinese  court,and correspondents  of  the French Academy Royale  des  Sciences.They  were given the title of “the King’s  hematicians”.This paper analyses  the  motivations  of  the scientific mission，the first ever sent from European  to China，the role of the  French Jesuits in  China  and some aspects of  their  contribution to European science.