Abstract: Using multicomponent mixture as refrigerant in the low temperature throttle refrigeration system can improve the total performance greatly.Former research work shows that there will be composition shift in the refrigeration system due to different reasons.Therefore,the circulating composition is finally different from the initial charged composition.It will lead to a different performance of the system.A sensitivity analysis is made in this work to know the influence of different components on the total performance.The results show that there are key components in the mixtures.That is the composition variation of the key component will greatly influence the thermodynamic performance of the system.The analysis will be useful in the future design of such system and be helpful in the understanding the work mechanism of the mixture refrigeration system.