This research investigates the implementation of portfolio assessment. The writer focused in the title of this research: “The Use Of Portofolio Assessment For Students Descriptive Writing Process At Eight Grade Students Of SMP PGRI 64 Surabaya The research is conducted based on the statement 1). How is the implementation of portfolio assessment in teaching writing descriptive text? 2). How are the students’ responses to the implementation of portfolio assessment in teaching writing descriptive text? and the objectives of the research are: 1). To describe the implementation portofolio asessessment in teaching descriptive text., 2). To describe the students response to the implementation of portofolio assessment in teaching descriptive text. The method of this research is Case Study which uses process follow: observation checklist and quesionaire. For doing this research the writer has chosen second grade class in SMP PGRI 64 Surabaya as the subject of the research and consists of 25 students. The writer conducted this research from October 4th to 18th October 2019. From the process of case study conducted, the writer concludes that the the implementation of portfolio assessment makes the students’ writing descriptive text ability become better or not. In the teaching and learning process, after the teacher asked the students to write descriptive text, the teacher would give some comments, notes, and revisions. In analyzing the students’ writing, the teacher implemented portfolio assessment and analyzed based on ESL composition profile by Jacob in Weigle (2002). Here, the implementation of portfolio assessment has fulfilled to make the students’ writing became better than before. The result of this research is the teacher can implement the portfolio assessment in student’s writing skill.