The COVID-19 pandemic poses a threat to the sustainability of higher education. Connectedness and engagement, two characteristics crucial to design education, have weakened significantly in online courses. However, limited research has been conducted on online design education than on STEM fields. Based on the dual coding theory, the purpose of this study was to use non-verbal tools to enhance design student connectedness and engagement in online class communication. In a quasi-experiment, 122 design students from a Chinese university were questioned and analyzed. They were randomly assigned to four different teaching situations and the effectiveness of two non-verbal tools was tested: emoticons and shared whiteboards. The ANOVA revealed a positive correlation between the use of non-verbal information in online class communication and the connectedness and engagement of design students. Moreover, the students in the group who used plentiful personified-form emoticons gave feedback and reported a stronger sense of connectedness and engagement. The whiteboard group’s data did not significantly differ from the control group, unlike the STEM discipline. To better develop the sustainability of design education, we provide recommendations for the design of online-education software and the method of online design instruction.