The present disclosure discloses a networking method device and terminal for an air conditioning unit. The networking method includes: detecting an outside ambient temperature after a target networking indoor unit is started; determining a target operating mode of the target networking indoor unit according to the outside ambient temperature; detecting a system pressure value of a multi-split air conditioning system after an operating duration of the target networking indoor unit in the target operating mode is greater than a preset operating duration; and determining whether the target networking indoor unit belongs to a target networking system according to the system pressure value.