The internal space of the space capsule is narrow, and the deep space is large. There are many kinds of equipment to be installed, large batches, heavy loads, and high assembly risks. In order to meet the requirements of automatic assembly of equipment in the spacecraft cabin and obtain an assembly robot with small structure size, large workspace, high load capacity and high flexibility, a lightweight, high load 8-DOF hybrid attitude adjustment robot cabin assembly system based on PRR/PR (PRR) R mechanism was proposed. The position mapping relationship, velocity mapping relationship, Jacobian matrix, acceleration mapping relationship of the hybrid assembly robot are analyzed. The dynamic model of the hybrid assembly robot is established, and the mapping relationship between the driving force, driving torque and joint speed is obtained. The stiffness model of the hybrid robot is established to solve the deformation degree of the mechanism after the six dimensional force is applied to the end of the mechanism. The kinematics and dynamics theoretical calculation results of the parallel mechanism are verified by the ADAMS simulation model. The theoretical stiffness model is verified by ANSYS finite element simulation. It provides a feasible scheme and theoretical basis for the realization of large equipment assembly automation in a narrow and long space.