To address the challenges of deploying traditional industrial robots and mitigating high-risk manual operations in complex constrained environments such as earthquake rescue, aircraft maintenance, and nuclear facility inspection, hyper-redundant robots have emerged as a research focus due to their exceptional flexibility and environmental adaptability. However, conventional hyper-redundant manipulators based on universal joint-linkage structures exhibit limitations in redundant degrees of freedom and low actuation efficiency when traversing long-distance pipelines or isolation zones. An extensible arm structure design was innovatively proposed to reconfigure the distribution of degrees of freedom and optimize the kinematic model, enabling the robot to penetrate extended isolation areas while maintaining high-precision end-effector manipulation and compact coiling capability in standby mode. Furthermore, the workspace of the proposed robot was quantitatively analyzed using the Monte Carlo method, with experimental results demonstrating that the workspace volume of the extensible hyper-redundant manipulator is approximately 1.78 times that of conventional hyper-redundant arms. Finally, the flexible motion characteristics of the robotic arm's end-effector were validated through kinematic simulations and physical prototype experiments. The developed extensible hyper-redundant robotic system provides a technically advanced solution for detection and sampling tasks in complex confined environments with isolation barriers, offering significant advantages for applications in nuclear facility maintenance and aerospace inspection scenarios.