This research had aimed to produce Learning Material based on Guided Inquiry Model with PhET simulation that is feasible to fascilitate student’s science process skill of junior high school. The Learning instrument is developed by using 4-D model with a trial-design namely one group pre-tes – post-test design. In order to measure aplicability of the lesson plan, learning obstacles, the result of students learning in from of science process skill students responses to the developed lesson plan. The lesson plans have been tried out to 15 students of VIII-A class in the even semester of 2016/2017 academic year. The data collection applies data validation, observation, achievement tes, questionaries. The research data were analysed descriptively both qualitative, and quantitative. The results  showed: (1) the teaching and learning materials developed are valid; (2) learning implementation got a good category; (3) the student’s participation  in actively learning; (4) student’s science process skill showed high category, (5) the students give positive response with very good category toward teaching and learning process. Based on this results, it can be concluded that the set of learning materials based on guided inquiry model with PhET simulation have been developed are feasible to fascilitate  the student’s science process skill.