Abstract: A novel variable speed photovoltaic DC refrigeration（VSPVDR）system is proposed in this paper. In the VSPVDR system,the direct current generated by the PV panel is directly input to the DC compressor without the inverter,and the system composition does not include batteries and other energy storage devices,and the compressor speed changes with the radiation intensity. In the paper,a dynamic model is presented to simulate the behavior of the VSPVDR system,and several prototype experiments are conducted to validate the model. On this basis,the impacts of the compressor speed control strategy and signal amplification factor of the speed control module have been studied. Compared with the fixed speed mode,the cooling capacity of the variable speed mode increases by 32.57% and the average PV utilization efficiency increases by 51.75%. When the signal amplification factor increases by 1.2 times and1.4 times,the performance of the system increases significantly,so the performance of the refrigeration system can be changed by appropriately adjusting the signal amplification factor of the speed control module to achieve the purpose of optimization.