Disclosed in the present invention are a method for transmitting/receiving downlink data in a wireless communication system, and a device therefor. Specifically, a method of receiving downlink data by user equipment (UE) in a wireless communication system comprises the steps of: receiving configuration information; receiving downlink control information (DCI), the DCI comprising a transmission configuration indication (TCI) field, and multiple TCI states being indicated on the basis of the TCI field; and receiving multiple transmission occasions of an identical transport block on the basis of the DCI. The multiple transmission occasions are received through a time-domain resource on the basis of time division multiplexing (TDM), and the number of the multiple transmission occasions is determined on the basis of the number of the multiple TCI states.