Unlike traditional rigid robots, soft robots can deform in a wide range to suit environment and contact compliantly with operating objects. Therefore, soft robots have wide potential application prospects in terms of physical rehabilitation, minimally invasive surgery and other fields. In this paper, we present an omni-directional flexural inflatable flexible arm model, which consists of three independent controllable pneumatic components. The components have different elongations under the effect of pressure and flexible arm is bending deformation. Under ideal conditions, it can be achieved 90° bending and 360° twisting. Based on the Yeoh model of hyperelastic rubber material and the geometric analysis method, we present the mathematical model of the flexible arm and FEM capabilities. We use finite element analysis to simulate the actuation characteristics of these modules. We compared the analytical and computational results to experimental results and can be used for the future design and control of soft robotic actuators.