The purpose of this study was to examine the effectiveness of traditional versus problem based learning on high school Science Problem Solving skill. Two class of students were recruited from three classes of grade 7 students at one school in Northern Thailand. Using Pretest – Posttest Control Group Design, Student were assigned to an experimental (N=33) and a control (N=33). The research instruments were 1) Two pedagogical of lesson plans by using Problem Based Learning and 5E Model 2) The Science Problem Solving skill test. which were included 20 items of the multiple choice test. The finding showed that students’ Science Problem Solving skill in the experimental group were significantly higher than in the control group.