Teaching English focuses on four language skills namely listening, speaking, reading, and writing. Students are expected to master those four language skills. The main purpose of English teaching is to improve the students' skills in using the language in real communication. One of the productive skills that students have to be improved is writing. In writing process, the students are expected to write grammatically, express their idea, and make the conclusion as the steps to develop rhetorical devices in the written form. The teaching writing using group work discussion gave better result as indicated by the significant statistical t-test computation that the t-obtained is higher than t-table. It is showed by looking at t-obtained is higher than t-table. The result of t-obtained is 11, 89 through the level of significant (5%). Then, the result of t-table is 1, 49. It means that the number of t-obtained is higher than t-table. The writer also concludes that the mean score of students' ability using group work discussion is 9, 05 and without using group work discussion is 4, 85. It means that group work discussion is effective to teach descriptive text to the seventh grade students of Junior High School.