Banyan optical networks play an important role in free-spatial photonic networks and optical communications. Based on previous research on the one-dimensional (1-D) Banyan network, the characteristics and structures of three-dimensional (3-D) Banyan networks are introduced and analyzed. Simultaneously, the experimental module of a 3-D Banyan network, which is integrated with a polarizing beam-splitter, 4×4 micro blazed-grating array plane, half-silvered mirror, 4×4 spatial light modulator, and mirror, is proposed and demonstrated. The 4×4 micro blazed-grating array plane can fulfill the vertical and horizontal connections of the 3-D Banyan network, and the mirror provides the straight connections. The theoretical analysis shows that the experimental setup can accomplish some functions such as optical signal switch, multicast, broadcast, and the 4×4 matrix conversion, and has advantages of compact in structure, low crosstalk, high speed, and efficient performance. Therefore, the designed experimental module of 3-D Banyan network can be implemented in free-spatial optical interconnection networks and optical signal processing.