Students' conceptions of learning science and their relations with motive for learning may vary as the education level increases. This study aimed to compare the quantitative patterns in students' conceptions of learning science (COLS) and motives for learning science (MLS) across grade levels by adopting two survey instruments. A total of 768 high school students were surveyed in Taiwan, including 204 eighth graders, 262 tenth graders, and 302 12th graders. In the current research, "memorizing," "testing," and "calculating and practicing" were categorized as reproductive conceptions of learning science, while "increase of knowledge," "applying," "understanding" and "seeing-in-a-new-way" were regarded as constructivist conceptions. The results of multivariate analyses of variance (MANOVA) revealed that conceptions of learning science are more constructivist as education level increases. Both tenth graders and 12th graders endorsed "understanding," "seeing-in-a-new-way," and the constructivist COLS composite more strongly than the eighth graders did. In addition, the results of multigroup structural equation modeling (SEM) analysis indicated that the positive relations between "testing" and reproductive COLS were stronger as the grade level increased, while the negative relations between reproductive COLS and "deep motive" were tighter with the increase in grade level.