The work aims to carry out aging-friendly upgrading of smart home appliances to enhance the user experience of the elderly. An interaction design methodology for ageing-friendly smart home appliances based on failure mode and effect analysis (FMEA) and root cause analysis (RCA) was proposed. First, the failure modes were identified by constructing a user journey map of smart home appliances used by the elderly to analyze the failure modes by FMEA, and evaluate the risk priority number; Second, a Pareto chart was drawn to identify the key failure modes according to the risk priority number, and analyze the root causes by Ishikawa Diagram; Then, the interaction design of smart home appliances was improved based on the root causes; Finally, the improved design was tested and the improvement effect was evaluated. The smart washing machine is selected as a case study, and the results show that the proposed method can effectively identify the failure modes of smart home appliances used by the elderly and analyze their root causes, which can provide a methodological reference for the optimization of the design of ageing-adapted smart home appliances and help the elderly to enjoy the technological dividend and cross the digital divide.