Bridges were destroyed or damaged by natural disasters, resulting in disruption of traffic. In order to improve the traffic recovery ability and solve the problems of heavy weight and inconvenient transportation of assembled steel Bailey beam bridges with common emergency equipment, a lightweight, easy-to-transport and fast-erection bridge structure can be explored. Therefore, an alternative structural design plan for lightweight prefabricated prestressed aluminum alloy bridges is put forth. These bridges are typically utilized in emergency situations for small and medium spans. The research has determined the structural form, main truss form, main truss parameters, crossbeam parameters, prestressed tendon types, and bridge deck parameters of rapid prefabricated small and medium span emergency bridges made of aluminum alloy. The structural calculation and analysis indicate that the prefabricated aluminum alloy bridge meets the standard requirements for both strength and stiffness. The utilization of prefabricated prestressed aluminum alloy bridges in the design offers several advantages, including less material usage, reduced maintenance expenses, and the possibility to be reused, resulting in significant economic benefits.