The study designed to answer the following two questions: 1 - How effective is the Six Thinking Hats Strategy on Mathematics achievement of grade six students of basic education? 2- How effective is the Six Thinking Hats Strategy on the Lateral Thinking of grade six students of basic education? The study sample consisted of (54) students of grade six basic education and was divided into two groups, experiment and control. The experiment group was selected from Mohammed Bin Sulaiman basic education School, while the control group was selected from Falah Bin Mohsin basic education School. Both Schools belong to the General Directorate of Education in Al-dhahira Governorated, Sultanate of Oman. To achieved the aims of this study, A Teacher guidebook was prepared by the researcher. In addition, two exams on achievement and Lateral Thinking were Performed. The study result showed the following: There was a statistical significant difference between the average score of the two groups in the achievement exam. The experiment group achieved higher score than the control group. There was a statistical significant difference between the average score of the two groups in the Lateral Thinking exam. The experiment group achieved higher score than the control group. The study recommended the training of the education supervisors and mathematics teachers on the use and implementation of the Six Thinking Hats Strategy on their teaching. It also suggested that more and further researches should be conducted on this thinking strategy to study other variables related to the teaching and learning mathematics.