Folding joint and trolley

The utility model provides a folding joint and a trolley. The folding joint comprises a folding joint body, a first connecting part and a second connecting part, the first connecting part and the second connecting part are overlapped with each other and are hinged through a connecting shaft perpendicular to the overlapping surface; a first groove is formed in the first connecting part; a sliding block is arranged in the first groove; the sliding block can reciprocate relative to the first connecting part in the direction perpendicular to the overlapping surface; wherein the first connecting part is provided with a first groove matched with the end of the sliding block in shape, the second connecting part is provided with a second groove matched with the end of the sliding block in shape, the second groove corresponds to the sliding block in position when the first connecting part and the second connecting part relatively rotate to a certain position, and the control unit is used for controlling the position o