Abstract: A software actuator that can meet the output force of message is proposed on the basis of the biological structure of an elephant's nose to satisfy the output force equipment of a massage robot. The output force of the soft actuator is mainly determined by eight internal factors, such as the length, diameter, and material properties of the actuator, and four external factors, such as the fiber wire material, the number of winding loops of the fiber wire, and the initial braiding angle. According to Hagen-Poiseuille's law, the relationship among pressure, cavity diameter, and actuator length is analyzed. The method of limiting the radial deformation is determined by discussing the winding ways of the fiber wire inside the actuator. The theoretical model of the actuator's output force is established by using the geometric equation and the moment balance equation after the actuator deforms. The optimal parameters of the actuator structure are determined on the basis of the theoretical model and the simulation model generated by the Abaqus simulation software. When the pressure is lower than 6 kPa, the experimental results are in good agreement with the theoretical model under the optimal parameters. Therefore, the theoretical model is accurate.