Plasma equilibrium is critical for experimental operation and data analysis in tokamaks. The number and location of magnetic diagnostics provide the magnetic field and flux information that influences the accuracy of the plasma equilibrium reconstruction. In this research, the truncated singular value decomposition method is applied to minimize the number of magnetic diagnostics for plasma equilibrium reconstruction based on Experimental Advanced Superconducting Tokamak existing magnetic diagnostics system. The reconstructed results with a reduced number of magnetic diagnostics are consistent with results obtained using full magnetic diagnostics by EFIT code. This implies that the approach of minimizing the number of magnetic diagnostics in reconstruction can reduce the demand for magnetic diagnostics while ensuring the accuracy of plasma equilibrium reconstruction with feasibility and reliability. Reduced magnetic diagnostics can increase tolerance for the absence of certain existing magnetic diagnostics and could be a reference for the redundancy design of magnetic diagnostics system in future fusion devices.