Distributed radar， as a new type of radar， is characterized by strong maneuverability and high signal-to-noise ratio gain. Its radar architecture can be divided into open-loop architecture and closed-loop architecture. The former has become a hot research topic in recent years due to its higher applicability and potential. The difficulty in implementing distributed radar with open-loop architecture lies in the decoherence of unit radar signals caused by error factors such as time and phase synchronization errors and baseline calibration errors. Due to the sparsity of aperture in distributed radar， it is difficult to effectively correct errors in an open-loop architecture. In response to the above issues， this paper analyzed the error factors in open-loop architecture and established corresponding error models. To achieve more efficient estimation of errors， an error estimation method based on an article swarm algorithm was proposed. The correctness of the method was verified by simulation experiments， and the corresponding relationship between synthesis efficiency and calibrated signal-to-noise ratio was obtained. This study provides a reference for the engineering implementation of distributed radar with an open-loop architecture.