Radiation therapy stands as a crucial method in treating lung cancer. However, the spatial movement of lung tumor by the respiratory movement presents challenge to precision radiotherapy. Aiming at the problem of extra radiation doses to healthy tissues caused by image guidance in current precision radiation therapy, this paper proposes an idea to simulate the respiratory deformation of the lungs in vitro by using a lung-like soft actuator. By modeling and predicting the motion of lung tumors, this approach aims to reduce the additional radiation dose to patients, thereby achieving accurate and safe radiation therapy. Firstly, the CT imaging is used to reconstruct the lung′s shape accurately, capturing the deformation motion pattern of the lungs during respiration. On this basis, the morphology of the lung cavity is designed and the structural design′s feasibility is verified through deformation simulation. A prototype of the lungmimicking soft actuator is then developed. Finally, the prototype is tested by giving discrete periodic air pressure to simulate the actual respiratory process. The experimental results show that the designed lung-like soft actuator can simulate respiration deformation as expected, with the maximum air pressure of 45 kPa, the maximum axial displacement of 5. 9 mm, and the maximum radial displacement of 3. 4 mm. The soft actuator exhibits good deformation mimics performance, and can be used as a reference of accurate and safe radiation therapy for lung tumors.