The aim of this research was to find out if the Problem Based Learning could imrove students’ ability writing descriptive texts at VII A class of SMP Negeri 1 Gumukmas. The participants were 32 students. The data was collected by using observation checklist and field notes. The test was use subjective test. After accomplishing this research, the writer concludes that the use of Problem Based Learning in writing descriptive texts can improve the students’ writing ability. The result of writing test in cycle one show the average score of students was 69,5.and the result of writing test in cycle two show the average score of students was 78. It means that in cycle two the students achieve the target and the research in cycle two is successful. It was proved that the use Problem Based Learning could improve the students’ ability writing descriptive texts. The students are more active and have a great motivation during the process of teaching and learning since they are free explore their ideas and share to their friends. Applying Problem Based Learning could imrove students’ ability writing descriptive texts in terms of grammar, vocabulary, and mrchanics.