Insufficient yield stress and electrorheological (ER) efficiency have already become the limitations for the practical application of ER fluids. Herein, we report a simple and scalable co-precipitation method for synthesizing surfactant-modified calcium titanyl oxalate (SCTO) particles with a rod-like structure. The obtained SCTO materials not only present a yield stress twice as that of granular CTO ER fluids but also demonstrate low zero-field viscosity, which results in a high ER efficiency. In terms of microstructure and dielectric analysis, we infer that the exceptional ER activity is in large part due the anisotropic morphology and improved wettability of the rod-like SCTO. This work provides the basis for the future development of ER fluids and the promotion of their practical application.