Trailer brake mechanism and outdoor trailer

The outdoor trailer comprises a frame main body and the trailer brake mechanism, the trailer brake mechanism comprises a trundle frame, wheels and a brake piece, the wheels are provided with hubs and are rotationally connected to the trundle frame through the hubs, the hubs are provided with a plurality of rib plate parts, and the rib plate parts are connected to the trundle frame through the brake piece. The multiple rib plate parts are evenly distributed around the rotating axis of the wheel at intervals, the brake part is movably connected to the trundle frame, the brake part is provided with a locking pin, and the brake part can move relative to the trundle frame so that the locking pin can stretch into the position between the two adjacent rib plate parts and can abut against the rib plate parts to limit rotation of the wheel relative to the trundle frame. In the braking process, the locking pin extends into the position between every two adjacent rib plate parts and can abut against the rib plate parts,