Abstract—A soft pneumatic actuator is a soft robotics part that significantly increases ability of a robotic arm to grasp an object in the automatic production line. To grip an object of various sizes and shapes, the bending angle of the actuator is a parameter that affects the grasping area and positioning of a robotic arm while applying air pressure. In this study, the actuator models with small and large cross-section ratios are compared by simulation using the finite element method. The simulation results show that increasing of the model cross-section ratio provides the wider bending angle than the reduced cross-section ratio model or the basic configuration model at the same input pressure. The proposed model still maintains the air surface area inside the actuator. Furthermore, it was found that the reduced cross-section ratio model has the most significant influence on the bending angle than the other models. Thus, the model comparison in term of the cross-section ratio is helpful to design the most effective gripper.