Cooling system of high and low temperature testing machine

The utility model relates to the technical field of refrigerating machines, in particular to a cooling system of a high and low temperature testing machine. The liquid storage tank is communicated with the condenser, the economizer is communicated with the liquid storage tank, the evaporator is communicated with the economizer, the economizer is further communicated with a pre-cooling evaporator, and the economizer is connected to the lower right liquid inlet end of the pre-cooling evaporator. The left upper liquid outlet end of the pre-cooling evaporator is further communicated with the left liquid inlet end of the evaporator, the left liquid outlet end of the evaporator is communicated with the right upper liquid inlet end of the pre-cooling evaporator, and the right upper liquid inlet end of the pre-cooling evaporator is communicated with the left lower liquid outlet end of the pre-cooling evaporator. The utility model has the beneficial effects that a group of pre-cooling evaporators are additionally arra