The study aimed to examine how emotional design and digitalization/mobilization of textbooks influence students' emotion, cognitive load, and cognitive performance. Research samples were 147 undergraduate students enrolling in the "Introduction to Internet" course at a university. They were randomly divided into three groups: 51 students in the control group using traditional paper textbooks; 49 students in the experimental group I using e-textbooks with emotional design; 47 students in the experimental group II consisted using e-textbooks without emotional design. The MANCOVA was adopted to analyze gathered data. The results revealed learners' positive emotion was significantly higher when using e-textbooks with emotional design than when using paper textbooks. Three types of cognitive load was significantly better when using e-textbooks with emotional design than when using e-textbooks without emotional design and paper textbooks. Cognitive efficiency was significantly better when using two types of e-textbooks (with and without emotional design) than when using paper textbooks. In a word, "emotional design and digitalization/mobilization" of textbooks (i.e. e-textbooks with emotional design) would significantly improve positive emotion; emotional design would significantly decrease intrinsic and extraneous cognitive load when using e-textbooks, and significantly increase germane cognitive load; digitalization/mobilization of textbooks (i.e. e-textbooks) significantly improved cognitive efficiency. What the study learned was that learners might firstly adopt e-textbooks with emotional design, and those without emotional design secondly, and paper textbooks rank last; viz., digitalized/mobilized textbooks (namely e-textbooks) were better than paper textbooks. Practical and theoretical implications and suggestions were raised for practitioners and researchers to take as references.