A method and apparatus for optimizing power consumption in multi-subscriber identity module (SIM) devices in a wireless communication system is disclosed. For example, a UE may determine, in a Multi-Subscriber Identity Module (SIM) Multi-Subscriber (MSMS) mode, whether one of a plurality of subscriptions is configured as a Default Data Subscription (DDS) or a non-DDS; and perform a carrier aggregation power saving mode procedure for the one of the plurality of subscriptions based on a determination that the one of the plurality of subscriptions is configured as the DDS or the non-DDS.