Space targets capture is an essential issue for space missions. This paper proposes a novel deployable grasping mechanism (DGM) that can be folded into a compact configuration for convenient transportation and deployed into an extensive configuration for grasping non-cooperative space targets. The DGM mainly consists of a series of serially connected basic deployable modules (BDMs). Each BDM is designed with a scissor mechanism and two parallelogram mechanisms. In order to deploy the BDMs synchronously, a unique connection mechanism is designed. The decoupled deployment motion and grasping motion enables the DGM to perform the capture operation at any motion state. For the proposed DGM, mobility, kinematics and stiffness analysis are performed. The characteristics and performance studied in this paper provide a basis for further investigation of the DGM in the area of space applications.