based on findings and discussion in this thesis, the researcher found that the difficulties of students to use coordinate conjunction is classified fair. their diffuclties are mostly distinguishing kinds of conjunction, confuse of the explanation from the lecturer, do not have guide book, do not know to put coordinate conjunction between dependent and independent clause, difficulty to distinguish the use of coordinate conjunction and sometimes forget to use conjunction in making sentence. in relation to this, it is suggested that the english learners need to improve their ability in using coordinate conjunction.