A collapsible horizontal vegetable processor comprises a base (1) and a cutter frame holder (13). The cutter frame holder is detachably provided with a replaceable cutter frame (2). The base is provided with a sliding rail mechanism. The base comprises a fixed portion (11) and a collapsible portion (12). The cutter frame holder (13) is arranged on one side of the fixed portion, and the collapsible portion is arranged on the other side of the fixed portion. The sliding rail mechanism is slidably provided with a sliding seat (4). The sliding seat is provided with a sliding seat frame body (5) and a handle (6). Pressing teeth (51) used to fix vegetables and a rotating operation device (52) are arranged at the top of the sliding seat frame body. The sliding seat is driven by the handle to move on the sliding rail mechanism. The base of the vegetable processor is collapsible, thereby greatly reducing an occupied space.