The work aims to improve the positioning accuracy of parallel robot in the packaging process. A positioning method of robot end-effector based on ADRC was designed. Two industrial cameras were configured on the basis of the traditional parallel robot structure. According to the binocular stereo vision detection principle, the specific position of block food on the production line was determined. An active disturbance rejection controller (ADRC), including tracking differentiator, nonlinear feedback controller and extended state observer, was designed to avoid interference factors reducing the grasping accuracy of the robot end-effector. Finally, the experimental platform was built and relevant verification was carried out. The experimental results showed that the maximum deviation distance between the actual position and the grasping position was 0.3 mm and the average error is only 0.20 mm. Compared with PID controller, the response time of ADRC only increased by 1%, but the average grasping accuracy was greatly improved. The positioning method of block food packaging based on parallel robot can make the end-effector reach the specified position in a very short time. The motion process is stable and reliable, without vibration, which can ensure the grasping accuracy.