Soft actuators are made of soft materials, and can realize movement through bending, contraction and extension of the soft elastomer material. Soft actuators are the key parts to realize the movement of biomimetic soft robots. Development of proper soft actuator is the prerequisite of biomimetic soft robot study. In order to develop biomimetic soft actuators which can be applied to soft robot, the structure of multi-chamber biomimetic pneumatic soft actuator is designed based on the common soft actuators structures. The main structure of the soft actuator was made of silicon rubber, and the actuator was fabricated by way of 3D printed mold. The main structure of soft actuators were affixed a base or combined to get extending actuators, unidirectional bending actuators and bidirectional bending actuators, which could deform like soft bodied animals do. The characteristics of the three soft actuators were tested. Results showed that the extending actuator has 40% extension under pressure of 15 kPa, and the bending actuator has large deformation under the same pressure. Practice proves that the principles of the multi-chamber biomimetic pneumatic soft actuators are feasible and the fabrication of the actuators is easy. The soft actuators can be applied widely in soft robots and other related areas.