The invention relates to the field of semitrailers, in particular to an automatic walking mechanism of a semitrailer container. The automatic walking mechanism comprises a frame, a container body, a container conveying device and a frame conveying device. The container conveying device and the frame conveying device are located behind the frame. The container body is the body for the container. The container conveying device comprises a forward conveying device and a backward conveying device. The forward conveying device and the backward conveying device each comprise a main conveying frame, a rotating shaft, a rotating frame, a rotating hydraulic rod, a connecting wheel hydraulic rod, a wheel frame, a spring and a container conveying wheel. The forward conveying device further comprises a forward conveying motor and a motor frame. The frame conveying device comprises a rotating disc, a connecting shaft, a supporting frame, a frame conveying motor, a first sliding rod, a second sliding rod, a connecting rod and a limiting plate. Automatic conveying of the container can be achieved, the container get away from the semitrailer horizontally and moved to the designated container placement region, no manual operation is needed, and the semitrailer body and cargos inside the container are effectively protected.