A method and a corresponding apparatus for performing uplink transmission in a wireless communication system are disclosed. The method comprises: based on at least one of the information indicating uplink transmission resources, acquiring the number of resource elements REs used for determining a PUSCH transmission; determining a transport block size TBS for the uplink transmission based on the number of REs; and performing the uplink transmission based on the determined TBS. Wherein, a PUSCH transmission occupies m time unit for transmission, and the rate matching and RE mapping of the PUSCH are performed on all resources occupied in m time unit.