In the context of the increasing aging population, design for the elderly has become more and more important. Many products have taken into consideration the elder-friendly design. However, the actual usability in real practice has not been sufficiently investigated. This study aims to tackle the problem and examine the practical usability of such a design through an experimental way. In particular, the Alipay app was selected as the target product to test. Its normal mode and elder-friendly mode were compared. For this purpose, we designed a set of experiments with 16 participants who are older than 45 years old and randomly divided them into two groups. One group used the normal mode, and the other used the elder-friendly mode. The eye tracker of Tobii Pro Glasses 2 was employed to collect participants’ eye movement data on these interfaces. Moreover, user interviews, user behavior observation, and System Usability Scale were jointly adopted to collect related user behavior information and subjective experience evaluation. Based on the qualitative and quantitative data, the differences between the two modes in the dimensions of information architecture, interface design, and task flow were identified. The results show that the current elder-friendly design cannot effectively facilitate usability for elderly users. Furthermore, the corresponding transdisciplinary design strategies were proposed to help with the improvement in design for the elderly.