Purposes: Investigating the contribution of each component of the Western Aphasia Battery (WAB) to the aphasia quotient (AQ) helps better understand the mechanisms of change in the AQ. Previous studies on patients with English-speaking aphasia have shown that spontaneous speech contributes the most to the AQ. However, the same conclusion may not be applicable to Chinese-speaking patients with aphasia because of the differences between Chinese and English languages. The primary objective of this study was to investigate differences between Chinese and English people with aphasia in the contribution of WAB components to the AQ. The second objective was to explore the effect of aphasia severity to the AQ. Methods: A total of 94 patients with Mandarin aphasia participated in this study. The Lmg and Pmvd algorithms based on relative weight analysis were conducted to calculate the contributions of the four main components and 10 subtests of the WAB to the AQ. Lmg measures the relative importance of each variable by allocating the explanatory power of the model, while Pmvd analyses through a decomposition method based on statistical explanatory quantities. In addition, the same method was applied to the severe, moderate and mild aphasia groups. Results: Of the four main components, naming contributed the most to the AQ, followed by spontaneous speech, listening comprehension and repetition. Object naming contributed the most among the 10 subtests. Among the different severity groups, naming contributed the most to the severe and moderate groups, while spontaneous speech contributed the most to the mild group. Conclusions: There were significant differences between Chinese and English patients with aphasia in terms of the contribution of each component of the WAB to the AQ. In Chinese, the largest contributor is naming, as opposed to spontaneous speech in English. Therefore, in a cross-linguistic context, it is important to carefully consider the impact of language differences, as this may help explain and understand the severity of Chinese aphasia.