In order to reduce energy consumption of chilled plant, a new control strategy with variable flow and variable temperature for allvariable chilled plant based on orthogonal experimental analysis is presented. The presentation and the implementation idea of that control strategy are firstly introduced. Secondly, a screw chiller model and a pump model are established, and these two models are then coded and embedded into the TRNSYS software to simulate and verify. Finally, a surfacewater chilled plant simulation platform composed of chillers and pump are developed based on TRNSYS. By using conducting quadratic orthogonal regression experiment on that platform, the empirical correlation formula between the total power of chilled plant and cooling load, supply cooling water temperature, cooling water flow, chilled water flow, and supply temperature of chilled water is obtained. By data processing, the optimized values of chilled water flow, cooling water flow, and supply temperature of chilled water which make the total power of chilled plant minimum under different cooling load and supply cooling water temperature are also gotten. Result shows that the new control strategy can decrease the power of chilled water plant by 4.94 kW and 14.023 kW respectively relative to the constant speed and the conventional variable speed, the saving power can increase by 54.6% relative to the corresponding conventional variable speed plant does.