A method of performing a random access (RA) procedure for a communication device in a wireless communication system is disclosed. The method comprises receiving first system information transmitted in a first subband resource of at least one subband resource by a network of the wireless communication system when performing a cell search procedure; receiving second system information transmitted in a second subband resource of the at least one subband resource according to the first system information, after performing the cell search procedure; and performing the RA procedure by using the second subband resource of the at least one subband resource according to at least one of the first system information and the second system information.