The grasping manipulator is a novel aerospace equipment developed for space debris capture， playing a crucial role in mitigating the growth of debris and effectively maintaining the space environment. In response to increasingly complex space mission requirements， a pressing demand has been identified in the aerospace field for new configurations of grasping manipulators with large operational ranges， multi-working-condition adaptability， and high flexibility. To address this， a modular octopus-inspired grasping manipulator with deployable and flexible characteristics is proposed， and its kinematic performance is investigated. First， by analyzing the muscular structure of an octopus tentacle， the mechanism underlying its flexible bending motion is elucidated， and a bio-inspired mapping relationship between the octopus tentacle and the manipulator is established， focusing on the kinematic functional dimension. Second， a Muscular-Hydrostats （M-H） unit with local motion characteristics similar to those of octopus arms is designed， and an n-PRP interconnected hyper-redundant mechanism with both deployable and bending functions is synthesized and optimized based on screw theory and graph theory. Third， under the constant curvature assumption， a multi-segment bending kinematic model for cable-driven systems is established using homogeneous coordinate transformation， accounting for complex coupling effects， and its workspace is analyzed. Finally， a prototype of the bionic manipulator is developed， and functional grasping experiments are conducted on target objects of various sizes and shapes. The results demonstrate that the proposed modular octopus-inspired manipulator exhibits variable-scale and multi-segment underactuated bending characteristics， along with variable backbone and self-adaptive capabilities. While meeting the fundamental requirements for satellite-borne launch， this manipulator enables large-scale and diversified grasping of various non-cooperative targets.