ABSTRAKSI The aims of this research are: (1) to improve the quality of teaching process of writing persuasion by using media public service advertisement at the class X-1 of SMA N I Mojolaban, (2) to improve the quality of students’ writing persuasion by using media public ervice advertisement at he class X-1 of SMA N I Mojolaban. The approach used in this research is a classroom action research. The subject of this research is class X-1 SMA N I Mojolaban which consist of 38 students. This research is conducted from the beginning survey, cycle 1, cycle 2, cycle 3, by the class teacher as the learning facilitator and the researcher as the passive participant. The technique of collecting data is conducted through the observation, writing test, questionnaire, interview, and document analysis. Each cycle cosist of four steps; (1) planning the action, (2) the action, (3) the observation and the interpretation, (4) the analysis and reflection. Based on the result if the research, it can be concluded that there is improvement of the quality of teaching process of writing persuasion by using media public service advertisement at the class X-1 of SMA N I Mojolaban. The improvement of quality process can be seeen from (1) the students’ activeness during the apperception, from 53 % in cycle I, to 65 % in cycle 2, an finnaly it reaches 77 % in cycle 3, (2) the students’ seriousness in paying attention to the teacher’s explanation, from 66 % in cycle 1, 69 % in cycle 2, and finnaly 83 % in cycle 3, (3) the students’ activeness in keeping a close watch on public service advertisement, from 83 % in cycle 1, 91 % in cycle 2, ad 97 % in cycle 3, (4) the students’ activeness in discussion, from 28 % in cycle 1, 33 % in cycle 2, and 41 % in cycle 3, (5) the students’ activeness in developing paragraph persuasion, from 83 % in cycle 1, 94 % in cycle 2, and 100 % I cycle 3. The improvement of quality of the result study can be seen from the students’ score which is keep on increasing to each cycle. At the beginning of the survey, the mean score for each cycle is 62.28 in cycle 1, 78.68 in cycle 2, and 79.22 in cycle 3. the perecentage of the completion of the study is also increasing from each cycle to the next cycle, that is, 55 % in cycle 1, 97 % in cycle 2, and 100 % in cycle 3.