Abstract: Distributed coherent radar on moving platforms can guarantee the mobility， scalability and low cost of the radar system while achieving high precision target estimation performance. Aiming at the position deviation and velocity deviation of the distributed coherent radar， the tightness of the hybrid Cramer-Rao bound （HCRB） is firstly analyzed in this paper. Then， the explicit expression of the angular estimation accuracy under the condition of unidentifiability is derived by using the HCRB. By solving the analytical solution formula， the influence of radar system parameters and topological parameters on the parameters to be estimated can be directly analyzed through the explicit expression， which is conducive to the selection and design of the hardware parameters of the radar system in the future.