The objective of this research are: (1) to find out whether picture series is effective use in teaching writing skill at tenth grade students of SMA Negeri 01 Balai in the academic year of 2018/2019; (2) to find out how strong the effect of using picture series to teach writing to the tenth grade students of SMA Negeri 01 Balai in academic year of 2018/2019. This was carried out at SMAN 01 Balai from 8 October to 8 November 2018. This research method was pre-experimental study. The subject of the research are the students of the tenth grade MIA students of SMAN 01 Balai. The class was consist 23 students. The procedure of research was one group pretest posttest. This research was conducted in three meeting. Technique to choose the sample was cluster random sampling. The sample tough by using picture series as the media. The data was obtained from test. The researcher gained quantitative data for his research. The students’ scores of students’ writing test was gained from pretest and posttest and the students ly have one time for treatment. The researcher analyzed using Microsoft Excel, then the researcher found out the numerical data of pretest score 65.3 and standard deviation 7. For the data posttest the researcher was gained the mean score 74 and standard deviation 4.6. T-test was shown the numerical data as follow; t-count 7.8289 and t-table 1.7171 it proved that using picture series in teaching writingskill is effective. and the effect level of using picture series in teaching writing skill based on data analysis was 0.75. Based on data analysis, the research finding are: (1) using picture series to teach writing to the tenth grade students of SMAN 01 Balai is effective; (2) The level of effect size got strong effect when teaching writing skill by using picture series. it can be concluded using picture series to teach writing skill is effective media to the tenth grade students of SMAN 01 Balai. The research have suggestion as follow: (1) for the teacher choose a suitable strategy, model, or media of teachi g and learning based the topic that going to learn; (2) for the students need pay attention, active, have a good communicate with other; for the reader and future researcher this thesis result could be an information and reference.