The invention belongs to the technical field of 
energy conservation, and relates to a variable frequency energy-saving control method for a 
refrigeration system. The control method comprises the steps of: determining the 
mass flow of a 
refrigerant according to the change or change trend of 
cooling load, then determining consumed power of a compressor which satisfies the flow, predicting the minimum condensation pressure which ensures that the 
thermal load of a condenser satisfies the 
cooling load and the power change of the compressor through an established energy-saving control 
mathematical model, and gradually adjusting the 
power frequency of the compressor to ensure that the rotating speed of the compressor reaches a predicted value; and adjusting the opening degree of an expansion valve to ensure that the condensation pressure reaches to be lowest, realizing the minimum 
pressure difference operation between the condenser and an 
evaporator, and ensuring that the operation 
energy consumption of the 
refrigeration system is lowest. The method solves the optimizing control problem of the compressor, the expansion valve and a 
fan in the 
system, utilizes the energy-saving control 
mathematical model to perform joint regulation on controllable factors (such as the rotating speed of the compressor, the opening degree of the expansion valve, and the 
air volume of an outdoor unit) of the operation of the system, ensures that the 
refrigeration system operates at a best 
operating point, and realizes the further 
energy conservation of the refrigeration system based on the variable 
frequency regulation.