The aimed of this study was to determine the effect of Project Based Learning Models on students’ learning environment and learning outcome in vocational High School. Samples were taken using cluster random sampling technique. This study used quasi-experimental method and involving a population of 142 students in the first year in automotive class from one of State Vocational High School in Surakarta. The sample was taken using cluster random sampling. Automotive class A with 36 students was used as the experimental class and automotive class B with 35 students as the control class. Data was collected using questionnaire, interview and test in the topic of rectilinear motion and circular motion. Data were analysed using descriptive and inferential analysis techniques using ANOVA. The results of this study showed that there was significant effect of project based learning model on students’ learning environment and outcomes. The project-based learning and learning environment has an interaction to determine the students learning outcome. Students tend to have better learning outcomes in good learning environment. Project-based learning successfully increases the learning environment significantly on indicators teacher-student relationships and Student-student relationships.