Students' attitudes towards science (SAS) is a prominent research area as evident in the science education literature. Many SAS studies incorporated science confidence (SC), science enjoyment (SE) and importance of science (IS) into the study of SAS. However, the incorporation of these constructs often depends on the subjective judgment of the researchers. This study examines the incorporation of the three constructs in the measure of SAS based on the Asian Student Attitudes Towards Science Class (ASATSC) instrument. A total of 1,133 7th to 11th graders from China completed a survey of the three constructs. Data was collectively assessed in terms of fit to the Rasch model that requires invariant and consistent response category functioning. Results indicated that SC was not correlated well with IS whilst SC and SE were consistent with each other in the measure of SAS. Recommendations were provided on how constructs on the measurement of SAS can be better designed.