Abstract: Taking a large commercial complex project as the research object, design optimization strategies is explored to solve problems such as large transformer capacity and unbalanced load rate in the project’s substation. The design optimization focuses on harmonic control and dynamic reactive power compensation, using a hybrid compensation device of active filtering and thyristor switched capacitors. The technical points of the optimization scheme are explained, and the optimization effect is evaluated. Research has shown that after optimization for substations, the transformer load rate ranges to 65%～73%; The total harmonic distortion rate is 4.2%, which is significantly lower than the 28% before optimization; The monthly average power factor reaches 0.96; The fault location time only takes 4 minutes, which is significantly shorter than the 45 minutes before optimization. The electrical design optimization plan for this substation is feasible, and the research content provides technical reference for the electrical design of substations in similar large commercial buildings.