<p>Currently, research in multi-body dynamics predominantly focuses on symmetric parallel mechanisms with multiple branches. However, for the working mechanism (WM) of a face-shovel hydraulic excavator, an asymmetric mechanism with multiple closed loops, there is a significant lack of research on dynamic models that account for the mass and inertia of all its moving components. The main focus of this study is to research a dynamic model of multi-closed-loop multi-body planar mechanism considering all moving components. This paper introduces a novel WM for a face-shovel excavator, featuring 4 loops and 12 links. By loop decomposition, the kinematic equations of the 11 primary moving components of the WM, including position, velocity, angular velocity, acceleration, and angular acceleration, are accurately formulated. For comparative analysis, a simplified dynamic model of WM was established, considering only the boom, stick, and bucket. The complete dynamic models based on the virtual work principle were also established. The correctness of both the simplified and complete dynamic models was verified through numerical simulations in Adams software. A comparison of simplified and complete dynamic simulation results shows that the new complete dynamic model has the advantage of accuracy. This research proposes a kinematic and dynamic modeling method with reference significance for the kinematic and dynamic analysis of planar complex multi-loop mechanisms, laying a foundation for performance analysis and the design of excavator WMs.</p>