Abstract: With the expansion of power system construction and the widespread application of underground utility tunnels, traditional cable trays have become inadequate in meeting modern engineering requirements regarding span, stiffness, and construction efficiency. To address this, this paper proposes a novel prefabricated cable tray structure design method suitable for spans up to 20 meters. The design utilizes a composite UHPC cable trough and steel truss system to achieve coordinated force distribution between concrete and steel materials. A force performance calculation model for the cable tray is established based on equivalent stiffness theory and finite element analysis. Field tests conducted on a distribution room demonstrate that this structure significantly outperforms traditional cable trays in load-bearing stability, construction efficiency, and cost-effectiveness, effectively enhancing the safety and standardization of power system support structures.