A communication device of handling an offload parameter according to a cell selection comprises a storage unit for storing instructions and a processing means coupled to the storage unit. The processing means is configured to execute the instructions stored in the storage unit. The instructions comprise receiving at least one dedicated wireless local area network (WLAN) offload parameter and a dedicated WLAN offload timer from a first cell in a connected mode; receiving a radio resource control (RRC) connection release message from the first cell; starting the dedicated WLAN offload timer; performing a cell selection procedure in response to the RRC connection release message; selecting a second cell according to the cell selection procedure; stopping the dedicated WLAN offload timer; and releasing the at least one dedicated WLAN offload parameter.