The work aims to propose a control strategy combing time delay estimation technique and adaptive integral sliding mode for trajectory tracking control in joint space of palletizing robot under unmodeled characteristics and load variation. According to the sorting requirements of round pieces, a desktop palletizing robot system was designed. The kinematics and dynamics models of the robot were derived to obtain the trajectory planning algorithm in joint space. Then, the trajectory tracking controller in joint space was designed based on the model-free idea. The joint angles of the robot were obtained by the Jacobi pseudo-inverse method and the trajectory of each joint was acquired through the proposed trajectory planning algorithm. Compared with PID controller and integral sliding mode controller, the proposed controller had better control accuracy, stronger disturbance rejection and higher robustness. The simulation and experiment results prove that the adaptive integral sliding mode controller designed based on time delay estimation technique is reasonable and can help the palletizing robot deal with the tasks of round pieces sorting, which has a certain engineering value.