Series elastic actuators (SEA) have great potential in robotic nondestructive grasping field due to its excellent force control performance. To achieve miniaturizing of the SEA, a highly compact series elastic actuator integrating servo motor, elastic element and encoder was developed. Firstly, model identification experiment of the series elastic actuator was carried out to establish the control angle trajectory actuating force observation models. Then the PD controller was utilized to control the actuating force. Subsequently, loading tests based on the rigid and hyperelastic objects were performed to study the control response, accuracy and steady-state fluctuation error of the actuating force. Finally, grasping and human interaction experiments were performed to study the adaptive grasping performance and external force self-sensing ability of the series elastic actuator. Results revealed that the series elastic actuator had a fast response speed in interacting with the rigid objects. The corresponding settling time and overshoot were about 0.35s and 0, respectively. Due to the nonlinear deformation characteristics of hyperelastic object, its loading response speed was smaller than that of the rigid one. Grasping experiments demonstrated that the SEA could achieve object grasping adaptively, and the grasping force and speed were adjustable. In addition, the SEA could realize selfperception of the grasping force without relying on fingertip force sensor, which was conducive to simplify the hardware and control system.