The utility model belongs to the field of medical equipment and especially relates to a pose-adjusting passive mechanical arm for a digestive endoscopic conveying robot. The pose-adjusting passive mechanical arm comprises a first arm rod, a second arm rod, five rotary joints and a digestive endoscopic conveying end. The five rotary joints are sequentially connected via connecting pieces. A third joint comprises a rotary joint. A fourth joint is provided with a connecting wheel disc. An air spring and a sprocket wheel transmission mechanism are also arranged on the second arm rod. One end of the air spring is hinged to the connecting wheel disc of the fourth joint. The connecting wheel disc is connected with the rotary joint of the third joint via the sprocket wheel transmission mechanism. Gravity balance of the second arm rod in a vertical direction is achieved via the air spring and the sprocket wheel transmission mechanism. Each rotary joint is internally and respectively provided with a band-type brake, an output shaft and a bearing. The pose-adjusting passive mechanical arm for the digestive endoscopic conveying robot has following beneficial effects: locking control of output shafts of the joints is achieved by connection and disconnection of band-type brakes; five degree of freedom adjustment via the rotary joints is achieved; and the need for pose-adjusting of the digestive endoscopic conveying robot is satisfied.