Infographics are a new type of reading material comprising textual and visual information that has been used worldwide. Nonetheless, there has been limited research investigating people's infographic-reading performance and the characteristics of superior readers. This study adopted Chinese texts and infographics as materials and employed eye-tracking technology to assess how working memory and relevant knowledge affected 137 college students' reading comprehension, as indicated by reading accuracy (ACC), and reading efficiency, which in turn was indicated by reading time (RT) and total fixation duration (TFD). For texts, verbal working memory (VWM) exhibited no effects on individuals' reading performance; visuospatial working memory (VSWM) exerted positive effects on both ACC and TFD, and participants with higher knowledge demonstrated better ACC. For infographics, higher-VWM participants showed greater ACC, and higher-VSWM participants displayed a longer RT and TFD, though the effect of knowledge was limited. Moreover, a significant interaction effect of VWM and relevant knowledge on the TFD of infographics was observed, indicating that individuals' prior knowledge or experience might structure schemas in an infographic and then act with VWM to accelerate reading speed. This study improves our understanding of how working memory and relevant knowledge impact the processing of materials with different synthesized levels, and its implications for instruction and research are discussed.