This study aimed to advance the Scientific Multi-Text Reading Comprehension Assessment (SMTRCA) by developing a rubric which consisted of 4 subscales: information retrieval, information generalization, information interpretation, and information integration. The assessment tool included 11 close-ended and 8 open-ended items and its rubric. Two texts describing opposing views of the dispute of whether to continue the Fourth Nuclear Power Plant construction in Taiwan were developed and 1535 grade 5-9 students read these two texts in a counterbalanced order and answered the test items. First, the results showed that the Cronbach's values were more than .9, indicating very good intra-rater consistency. The Kendall coefficient of concordance of the inter-rater reliability was larger than .8, denoting a consistent scoring pattern between raters. Second, the analysis of many-facet Rasch measurement showed that there were significant difference in rater severity, and both severe and lenient raters could distinguish high versus low-ability students effectively. The comparison of the rating scale model and the partial credit model indicated that each rater had a unique rating scale structure, meaning that the rating procedures involve human interpretation and evaluation during the scoring processes so that it is difficult to reach a machine-like consistency level. However, this is in line with expectations of typical human judgment processes. Third, the Cronbach's coefficient of the full assessment were above .85, denoting that the SMTRCA has high internal-consistency. Finally, confirmatory factory analysis showed that there was an acceptable goodness-of-fit among the SMTRCA. These results suggest that the SMTRCA was a useful tool for measuring multi-text reading comprehension abilities.