Air conditioning system and control method and device for refrigeration of air conditioning system

The invention provides an air conditioning system and a control method and device for refrigeration of the air conditioning system, relates to the field of air conditioners, and solves the technical problem that the refrigeration capacity of the air conditioning system is poor under the limit working condition of low-temperature refrigeration. The air conditioning system comprises a first refrigerating circuit and a second refrigerating circuit which are both used for allowing refrigerants to circulate, the first refrigerating circuit and the second refrigerating circuit are arranged in parallel, and the first refrigerating circuit and the second refrigerating circuit both have a conducting state and a blocking state with the same evaporator; a cooling liquid flow path is arranged on an outdoor heat exchange component of the first refrigerating circuit in a penetrating mode, and a refrigerant can exchange heat with outdoor air and cooling liquid when flowing through the outdoor heat exchange component. Only w