Disclosed are a data transmission method and apparatus, which are used for realizing low-delay and high-reliability transmission of data in a new radio (NR) system. The method comprises: determining an actual transmission opportunity in a transmission period according to a notification of a network side, and determining a first transmission opportunity on the basis of the actual transmission opportunity, wherein there are T valid transmission opportunities between the first transmission opportunity and a first moment, the valid transmission opportunities include an actual transmission opportunity with an RV of zero, and the first moment is before the end of the transmission period or before the start of a period of a second configuration authorization configuration; when data is ready before the first transmission opportunity and after the second transmission opportunity, starting data transmission at the first transmission opportunity, wherein the second transmission opportunity is the actual transmission opportunity before the first transmission opportunity; and when the data is ready after the first transmission opportunity, starting the data transmission in the next period. Therefore, a valid starting position may be determined according to a received signaling indication.