This study aims at knowing the results of using discovery learning in Imla’ and its effectiveness. The research method to be used was quantitative method with experimental design. Data were collected through tests, observation and documentation. The data were analyzed using statistical data analysis t test to determine the level of the effectiveness of discovery learning method. The obtained results illustrated that the discovery learning method in Imla’ consists of four stages including exposure, observation and analysis, preparation or formulation of linguistic rules, and application of rules. The application of discovery learning method was very effective in imla’ course because it can improve students' understanding of the materials, so that students can write hamzah wasal in the form a word or sentence properly and correctly. This can be seen from the results of the t test carried out in the pre-test and post-test values that the t value was greater than the t table, namely 2.09 <21.91> 2.86. Thus, H˳ is rejected, which means that the method is effective for improving students' writing skill.