Data increase written scientific argumentation from pre-action to second cycle has been increased according to the target is ≥30%. Percentage performance students written scientific argumentation in the second cycle increased to 86,55% with a very high category, consists of claim at 97,37% with a very high category, evidence at 85,97% with a very high category and reasoning at 76,31% with a high category. Percentage performance students written scientific argumentation in the first cycle increased to 57,89% with a medium category, consists of claim at 64,91% with a high category, evidence at 56,14% with a medium category and reasoning at 52,63% with a medium category. Percentage performance students written scientific argumentation in pre-action is 36,55% with a low category, consists of claim at 50,88% with a medium category, evidence at 35,09% with a low category and reasoning at 23,68% with a low category. The reasearch target was improvement of written scientific argumentation increase ≥30% from base line.The result showed the application of problem based learning can improve written scientific argumentation students at class X Science. The research procedure used eas the spiral method. The data was analyzed using descriptive analysis technique. The technique used to validate this data was triangulation method. Untuk memenuhi kebutuhan sandang, didirikan pabrik tekstil. Contohnya untuk memenuhi kebutuhan lahan pertanian, maka hutan dibuka dan rawa/lahan gambut dikeringkan. The main data about students written scientific argumentation covers three aspects, they are: claim, evidence, and reasoning. Pengaruh penerapan problem based learning terhadap literasi lingkungan siswa SMP pada materi pencemaran lingkungan. Aktivitas manusia dalam rangka memenuhi kebutuhan hidupnya sering menimbulkan dampak yang tidak baik pada lingkungan. Technique of collecting data used tests, interviews, and documentation. The subject of the research was 38 students of X Science.The source of the data came from teacher and students. It was carried out in two cycles in which each cycle consists of four stages: planning, action, observation, and reflection. The research was a Classroom Action Research (CAR). The research aims to improve students written scientific argumentation through the application of problem based learning into enviromental pollution main subject at class X Science.