The Effectiveness of Discovery Method in Idhafah and Na’at Sentence Arrangement of Insya Hur. (Experimental Research in Jeumala Amal College). Idhafah and Na’at specifically Nahwu are crucial elements in arabic learning that has to be learned by students before they produce the perfect Insya Hur. The students of Jeumala Amal not only found difficulties in learning Idhafah and Na’at but got bored as well. Thus, students had a very low ability. It was caused by the disagreement between method used by teacher and students’ condition. Based on these problems, Discovery Method was selected by researcher in order to increase students’ ability in Idhafah and Na’at. The purposes of this research are To identify students’ response toward Discovery Method in learning, and to find out students’ ability to produce Insya Hur with the right Idhafah and Na’at arrangement. Quantitative supported by qualitative approach along with experimental method was used by researcher. Purposive sampling was used to find the fifth graders of 5 IPA1 that was consisted of 34 students. The result is that the use of Discovery Method in learning Idhafah and Na’at was effective and it gave a good impact on students of Jeumala Amal College, which the result from the t-hitung related calculation is greater than t-tabel result, that is 2,83>1,99. Keywords : Discovery Method, Idhafah and Na’at, Insya Hur.