The use of self-regulated learning strategies tend to have an impact on student learning and achievement; however, the nature of this relationship for primary science achievement needs further investigation. The purpose of this study was to examine the relationship between learning strategies used by primary students and their science achievement. The use of learning strategies was measured by the 50-item modified version of the Motivated Strategies for Learning Questionnaire (MSLQ) and the science achievement was measured by a test compiled from the released TIMSS items. Bivariate correlation analysis results showed that among the nine learning strategies that were investigated, seven of them were significantly associated with the science achievement. There were no correlations between peer learning and help seeking and achievement. Multiple regression analysis results showed that among the seven strategies, effort regulation, metacognitive self-regulation and critical thinking significantly contributed to the science achievement. Results and implications for instruction were discussed.