As electro-hydrostatic actuator (EHA) technology advances towards lightweight and integration, the demand for enhanced internal flow pathways in hydraulic valve blocks intensifies. However, owing to the constraints imposed by traditional manufacturing processes, conventional hydraulic integrated valve blocks fail to satisfy the demands of a more compact channel layout and lower energy dissipation. Notably, the subjectivity in the arrangement of internal passages results in a time-consuming and labor-intensive process. This study employed additive manufacturing technology and the ant colony algorithm and B-spline curves for the meticulous design of internal passages within an aviation EHA valve block. The layout environment for the valve block passages was established, and path optimization was achieved using the ant colony algorithm, complemented by smoothing using B-spline curves. Three-dimensional modeling was performed using SolidWorks software, revealing a 10.03% reduction in volume for the optimized passages compared with the original passages. Computational fluid dynamics (CFD) simulations were performed using Fluent software, demonstrating that the algorithmically optimized passages effectively prevented the occurrence of vortices at right-angled locations, exhibited superior flow characteristics, and concurrently reduced pressure losses by 34.09%–36.36%. The small discrepancy between the experimental and simulation results validated the efficacy of the ant colony algorithm and B-spline curves in optimizing the passage design, offering a viable solution for channel design in additive manufacturing.