The research focused on the implementation of project basedlearning model in the learning physics. Purposes of this study were todescribe the student's science process skills during teaching and learningprocess and to investigate the student's achievement after learning physicsusing project based learning model better than the student's achievementafter learning physics using the usual model in Senior High School. Thetype of this research was true experiment with post test only control groupdesign. The population of this research were students of class X at SMAN 1Probolinggo (2015/2016). Technique to collect the data wereobservation, test, documentation, interview, and portofolio. The data ofstudent's achievement were analized by using Independent Sample T-Testwith the help of SPSS 22. The results of this research were: (1) the averageof percentage students' science process skills for experimental class fromKBM I dan II was 85.09%, (2) the result data of student's achievement byusing Independent Sample T-Test was H1 accepted, H0 rejected, it meansthe student's achievement after learning physics using project basedlearning model better than the student's achievement after learning physicsusing the usual model in Senior High School. The research can beconcluded that: the students' science process skills during teaching andlearning process was classified into very good criteria and the student'sachievement after learning physics using project based learning modelbetter than the student's achievement after learning physics using the usualmodel in Senior High School