This study was aimed to describe and analyze (1) understanding concepts and critical thinking skills difference between student that learned project-based model and conventional model, (2) understanding concept difference between student that learned project-based learning model and conventional model, (3) critical thinking skills difference between student that learned project-based model and conventional model.. This study included in quasi experiment with posttest only control group design. Sample was collected through simple random sampling in 11th grade student in SMA Negeri 2 Negara of academic year 2012/2013. The data were analyzed with multivariate analysis. The conclusion can be stated based on analysis result is (1) there was difference between understanding concepts and critical thinking skills as impct of project-based model and conventional model (Fcal = 13,921 > Ftable = 3,91). (2) there was difference between understanding concepts as impct of project-based model and conventional model (Fcal = 9,263 > Ftable = 3,91). (3) there was difference between critical thinking skills as impct of project-based model and conventional model (Fcal = 20,714 > Ftable = 3,91).