A communication method and system for converging a fifth generation (5G) communication system for supporting higher data rates beyond a fourth generation (4G) system with a technology for Internet of things (IoT) are provided. The communication method and system may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. A method of a terminal for performing a random access procedure in a wireless communication system is provided. A method includes identifying whether physical random access channel (PRACH) occasions are configured for an active uplink (UL) bandwidth part (BWP) of a serving cell; based on the PRACH occasions not being configured for the active UL BWP and the serving cell being a special cell (SpCell), switching an active downlink (DL) BWP of the SpCell; and performing the random access procedure on the active DL BWP of the SpCell and the active UL BWP of the serving cell. A method by a terminal for transmitting a message 3 (Msg3) in a random access procedure is provided. In addition, a method by a terminal for system information (SI) request is provided.