Abstract: Earthwork allocation is a critical aspect of hydropower project construction, directly impacting construction cost and efficiency. To optimize allocation strategies and enhance machinery utilization efficiency, this study proposes an optimization method for earthwork allocation and road transportation systems based on the coupling of the primal-dual interior point method and AnyLogic. First, a dynamic earthwork allocation model is formulated with the objective of minimizing allocation costs while considering constraints such as excavation and filling schedules and site planning. Second, given the complex road transportation conditions in hydropower projects, an AnyLogic-based road transportation system simulation model is developed using queuing theory. The primal-dual interior point method is then employed to solve the dynamic earthwork allocation model, yielding an optimal allocation plan. Subsequently, the earthwork allocation model is coupled with the AnyLogic simulation model. By leveraging multi-agent simulation techniques, the dynamic interactions of construction machinery during transportation are simulated, enabling real-time data visualization and feedback. This facilitates dynamic adjustments to machinery allocation, thereby improving machinery utilization efficiency. Finally, the proposed method is applied to a practical engineering case. Results demonstrate that this approach effectively reduces earthwork allocation costs, lowering total project expenses by 7.3%. Additionally, it enhances machinery coordination efficiency, increasing the comprehensive embankment placement rate of the supply and receiving zones to 84.0% and 86.7%, respectively. The utilization rate of most backhoe excavators exceeds 60.0%, while that of dump trucks reaches over 95.0%. These findings provide strong support for decision-making in earthwork allocation planning.