A communication device for handling a user equipment, UE, access stratum, AS, context, comprising: a storage device, for storing instructions of: establishing a radio resource control, RRC, connection with a network; receiving the UE AS context from the network, wherein the UE AS context comprises at least one of a RRC configuration and a security context; receiving a RRCConnectionRelease message configuring the communication device to suspend the RRC connection and enter a RRC_IDLE state or configuring the communication device to enter a RRC_CONNECTED state with a RRC light connection from the network, after receiving the UE AS context; storing the UE AS context, when receiving the RRCConnectionRelease message; restoring the UE AS context, resuming a signalling radio bearer 1, SRB1, and transmitting a RRCConnectionResumeRequest message to the network, when initiating a RRC connection resume procedure; receiving a RRCConnectionSetup message or a RRCConnectionReject message in response to the RRCConnectionResumeRequest message from the network; and releasing the restored UE AS context and the resumed SRB1 in response to the RRCConnectionSetup message or the RRCConnectionReject message; and a processing circuit, coupled to the storage device, configured to execute the instructions stored in the storage device. a storage device, for storing instructions of: establishing a radio resource control, RRC, connection with a network; receiving the UE AS context from the network, wherein the UE AS context comprises at least one of a RRC configuration and a security context; receiving a RRCConnectionRelease message configuring the communication device to suspend the RRC connection and enter a RRC_IDLE state or configuring the communication device to enter a RRC_CONNECTED state with a RRC light connection from the network, after receiving the UE AS context; storing the UE AS context, when receiving the RRCConnectionRelease message; restoring the UE AS context, resuming a signalling radio bearer 1, SRB1, and transmitting a RRCConnectionResumeRequest message to the network, when initiating a RRC connection resume procedure; receiving a RRCConnectionSetup message or a RRCConnectionReject message in response to the RRCConnectionResumeRequest message from the network; and releasing the restored UE AS context and the resumed SRB1 in response to the RRCConnectionSetup message or the RRCConnectionReject message; and establishing a radio resource control, RRC, connection with a network; receiving the UE AS context from the network, wherein the UE AS context comprises at least one of a RRC configuration and a security context; receiving a RRCConnectionRelease message configuring the communication device to suspend the RRC connection and enter a RRC_IDLE state or configuring the communication device to enter a RRC_CONNECTED state with a RRC light connection from the network, after receiving the UE AS context; storing the UE AS context, when receiving the RRCConnectionRelease message; restoring the UE AS context, resuming a signalling radio bearer 1, SRB1, and transmitting a RRCConnectionResumeRequest message to the network, when initiating a RRC connection resume procedure; receiving a RRCConnectionSetup message or a RRCConnectionReject message in response to the RRCConnectionResumeRequest message from the network; and releasing the restored UE AS context and the resumed SRB1 in response to the RRCConnectionSetup message or the RRCConnectionReject message; and a processing circuit, coupled to the storage device, configured to execute the instructions stored in the storage device.