This study aimed at identifying the extent to which the environmental dimension of sustainable development is included in the science books of the second cycle (5-10) of the basic education in the Sultanate of Oman. To achieve this goal, the study tool was designed as a tool for analyzing the content of science books in light of five domains of environmental dimension of sustainable development: environmental pollution and controlling it, air protection, water protection, soil protection and sound management of the environment. Forty indicators are within these domains. To verify the validity of the content of the study tool, it was presented to a number of specialists in the field of science education and sustainable development, and was confirmed by the use of the equation "Kaba" between the two persons who analyzed the content, where it reached (92.5%), which is suitable for the purpose of analysis. The results of the study indicated that the extent of the environmental dimension of sustainable development in the science books for grades (5-10) of the basic education was different. The results showed that the contents of the analyzed books in general dealt with all five main domains of the environmental dimension of sustainable development included in the study tool, which was 100%. The seventh grade book included most of the domains, where all the five main domains dealt with 22%, followed by the tenth grade book by 20%, followed by the eighth grade book with 18.9% followed by the sixth grade book (14.9%), then the ninth grade book by percentage of (8%), and finally the fifth grade book (4.9%). The study recommended that the domains related to water protection, air protection and soil protection should be included more in the curriculum, which did not appear significantly in the analyzed books due to their deep role in achieving sustainable development in the Sultanate of Oman.