Abstract: The paper focuses on the separation and deployment dynamics of an on-orbit compactly connected multi-rigid-body (MRB) system, which could separate autonomously from a carrier spacecraft. Based on the focused MRB system, it is not necessary to repeatedly use the launcher of the carrier spacecraft or install multiple launchers in the spacecraft to separate the MRB system. This is advantageous because it can effectively improve the space utilization rate of the spacecraft, simplify the separation deployment operations and reduce the risk of collision between rigid bodies. To realize the separation of such a MRB system, the paper presents an investigation on its on-orbit dynamics and the design of collision-free separation deployment schemes. Firstly, a dynamic model of a single rigid body is established based on the principle of virtual work and the Natural Coordinate Formulation (NCF) method accounting for the relative motion between rigid bodies and attitude changes of each rigid body. Considering the orbital motion, the variations of connecting constraints of the MRB system and the interactions between rigid bodies during the separation, the governing nonlinear dynamic equations including constraints of the system are obtained with a method of Lagrange multipliers. With practical engineering applications taken into consideration, the separation deployment of MRB system is realized through ejection mechanisms mounted on the four corners of each contact surface between rigid bodies. Secondly, the timing sequences of separation maneuvers are specially programmed and two separation schemes are developed by adjusting different ejection directions and ejection sequences to guarantee the non-collision between rigid bodies in the separation deployment. Finally, numerical case studies are presented for investigating the nonlinear dynamic behaviors of rigid bodies and demonstrating the effectiveness of separation schemes.