This study aimed to describe find out the influence of using problems solving method towards student's rational thinking ability in economic learning. This study use quasi experiment method with nonequivalent group pretest-posttest design. The study population is class XI students of social study departement, even semester, 2008/2009 academic year. Sample is determined randomly. Experiment class in this study is class XI IPS 2 students and control class is class XI IPS 4 students. Research instrument that is used is rational thinking ability test, questionaire and observation guidance. Hypothesis analysis with test use SPSS version 16.The study result shows that there is no significant difference of students' rational thinking skill with expriment class with control class on initial measurement (pre-test), there is significant difference of students' rational thinking skill between experiment class with control class on final measurement (post-test), there is significant difference between pre-test and post-test result on experiment class with problems solving methods treatment , there is no significant difference on students' rational thinking ability between class that get problems solving method treatment with class which not get problems solving method treatment.