The three-axle side-lift self-loading & unloading semi-trailer integrates a high-strength hydraulic side-lifting crane mechanism and an extendable lengthened frame system. It requires no external lifting equipment such as reach stackers, forklifts or gantry cranes throughout operation. A single driver can independently complete the full set of container handling procedures including lifting, positioning, lowering and locking via wireless remote control. Equipped with a telescopic locking structure, the frame allows flexible length adjustment. In standard configuration, it fits 20ft standard containers. When extended to 14 meters, it stably carries large-size 40GP/40HQ containers, enabling one trailer to accommodate the two mainstream container types.