This study aims to explore how e-textbooks with emotional design affect students' emotion, cognitive load and learning achievement. There were 147 freshman students in total: the experimental group I, II and control group consisted of 49, 47 and 51 students, using e-textbooks with emotional design, without emotional design and traditional paper textbooks. The results reveal the following: Students' emotion after using e-textbooks with emotional design is more positive than those using e-textbooks without emotional design and paper textbooks. Students' cognitive load after using e-textbooks with emotional design is significantly lower than those using etextbooks without emotional design. Students' learning achievement after using two types of e-textbooks is better than after using paper textbooks. Comparing all types of textbooks altogether, emotion has a significantly positive correlation with learning achievement, and both emotion and learnng achievement are significantly and negatively correlated with cognitive load. For the three types of textbooks, the relationship between emotion and learning achievement all becomes not significantly correlated. For two types of e-textbooks, cognitive load and learning achievement become not significantly correlated, disturbed by the digitalization of textbooks. Instructors are suggested to firstly adopt e-textbooks with emotional design, those without emotional design secondly, and paper textbooks rank last.