Background: In the field of science education, the importance of assessment in students' learning process has been recognized. Understanding of how students perceive science assessment and feedback may be an important issue that science education researchers need to pay attention to in order to achieve meaningful learning. Purpose: The purpose of this study is to investigate the relationships between lower secondary students' perceptions of science assessment feedback and their conceptions of science assessment. Sample: The participants of this survey study were 313 eighth-grade students (161 males and 152 females) in Taiwan. Design and methods: Two instruments were adapted and implemented to investigate the aim of this study (i.e. the perceptions of science assessment feedback and conceptions of science assessment). To examine the structural relations between the students' perceptions of science assessment feedback and their conceptions of science assessment, partial least squares structural equation modeling (PLS-SEM) analysis was performed. Results: The results showed that students who perceived the science assessment feedback as knowledge of the results, reports, and grades (i.e. outcome feedback) tended to highlight the surface conceptions of science assessment (i.e. Reproducing knowledge). Students with the perceptions of assessment feedback as the provision of the correct answer (i.e. corrective feedback) were prone to hold summative conceptions (i.e. Rehearsing and Accountability). In particular, those students who regarded the science assessment feedback as process feedback which focused on improving learning may have had both summative and formative purposes of science assessment (i.e. Improving learning, Problem solving, and Critical judgment). Conclusions: The findings revealed that the lower secondary students' perceptions of science assessment feedback made a significant contribution to their conceptions of science assessment and may be in a transitional phase of shaping an understanding of assessment. The practical implications and suggestions for future research are discussed.