The study aimed to investigate the effect of using Graphic Organizer Strategy in the mathematical problem-solving among ninth grade students and their beliefs towards learning it. The researcher followed the quasi experimental approach. The study was applied to a sample of (44) students from the ninth-grade students. The sample was divided into two groups, one is experimental group consisted of (22) students who taught using the graphic organizer strategy, and the other is the control group consisted of (22) students who were taught in the usual way. To achieve the objectives of the study, the researcher prepared the teacher's guide of the sixth unit "Equations and Functions" for the ninth grade according to the graphic organizer's strategy. The two instruments applied in this study were Mathematical Problem-Solving Test (prepared by the researcher) and students' beliefs scale towards mathematical problems solving. The results of the study showed that there were statistically significant differences at the level of significance (a=0.05) between the average score of the experimental group students and the average score of the control group students in each of the mathematical problem-solving tests, and the scale of beliefs toward mathematical problem- solving in favor of the experimental group that was taught using the graphic organizer strategy. In light of these results, the researcher recommended the necessity of developing mathematical problem-solving skills among students, using appropriate strategies for that in order to enhance students' beliefs towards mathematical problem- solving. The study also recommended conducting further research on the use of graphic organizers in Mathematics.