Abstract: In gastroscope operation, there exist the problems of high difficulty, heavy working intensity of endoscopists, risks of digestive fluids' pollution and X-ray radiation. To solve those problems, a robot-assisted master-slave system for gastroscope intervention is developed. Through sufficient analyses on characteristics of clinician manual manipulation of gastroscope, the system is divided into two parts, gastroscope delivery arm and gastroscope operation arm. The delivery arm adjusts the pose of gastroscope relative to patient mouth and implements the insertion. Inverse kinematic analysis of the passive arm for gastroscope delivery is conducted to determine the joint parameters and the position of the base. The force between gastroscope and delivery device is also analyzed to determine the output torque of motor for delivery. The operation arm steers the control section to realize gastroscope rotation, control section following, distal bending, insufflation, rinsing and suction. The intervention and operation of gastroscope are controlled remotely by a joystick which realizes the intuitive projection of motion between gastroscope and joystick. After the in vitro test experiments, in vivo experiments are carried out, in which the robotic system realize each operation for gastroscope without damage to the tissue. The experimental results show that the system can implement gastroscope intervention intuitively and effectively, and the ergonomic design significantly reduces the difficulty of the operation.