The current research aims to determine the requirements of Trends of International Mathematics and Science Study (TIMSS 2019) and to find out the extent to which the content of science textbooks for grades (1-4) in the Sultanate of Oman includes the requirements of (TIMSS 2019). Only the content dimension has been taken into account when conducting the content analysis. The study population includes all science books from the first to the fourth grade for the academic year 2021-2022. The study identified and organized the requirements in the study tool, which is a list of requirements of (TIMSS 2019). The results showed a general deficiency in all grades (1-4) in the content dimension including many main topics, subtopics, and objectives (performance indicators). The results also showed that only 22.80% of TIMSS 2019 requirements have been covered in grade 1, 40.35% in grade 2, 36.84% in grade 3, and 45.61% in grade 4. Additionally, the study discussed the percentage of inclusion of TIMSS 2019 standards in all books cumulatively and found amazingly that the percentage included is close to some extent for each of the three domains to the percentages specified by (TIMSS 2019) but over the course of the four years and not over a period of one year only, which means that the lack of inclusion in a field in one class has been compensated for in another class. The research recommends the need to review the content of science books for grades

(1-4) to make sure that they include the requirements of the TIMSS test that are not available in the content of the books and suggests conducting an analytical study of the same books for the dimension of cognitive processes