This is a great work that aims at confirming whether the autonomous vehicles (AV) for last-mile delivery is sustainable in terms of three aspects - social sustainability, environmental sustainability, and economic sustainability. This study finds that it is relatively safe to use AVs for delivery because of the speed limit of actual society and the good road conditions provide the ground that AV runs safely for last-mile delivery in urban areas. Besides, AV has a special advantage when facing pandemic. For environmental sustainability, the emission problem is the main concern. It is concluded that AV has a significant advantage in emission reduction in terms of a series of emissions. As for the economic sustainability of AV, this research adopted a quantitative way to illustrate because the cost of AV is essential to consider because of AV's commercial nature. The research reveals the cost advantage of AV under different carrying capabilities.