This application discloses a delay reduction method and apparatus, applied to a random access process. The method includes: sending, by a terminal device, a message 1 to a network device, where the message 1 is a random access preamble; receiving, by the terminal device, a message 2 sent by the network device; and sending, by the terminal device, a message 3 to the network device, where a time gap between receiving the message 2 and sending the message 3 is set by the terminal based on a timing advance (TA) value. In an embodiment, the TA value is related to a message 1 format of the terminal device and a cell radius or subcarrier spacing supported by the message 1. In this solution, a TA value is reduced, and random access efficiency is improved.
TA is a maximum delay supported by a 12-bit TAC (Time advance command in a RAR). Maximum TAs corresponding to different uplink subcarrier spacings of the message 3 are shown in the following table.