The implementations of the present disclosure relate to a random access method, a terminal device and a network device. The method includes: a terminal device receiving indication information sent by a network device, wherein the indication information is used for indicating at least one random access preamble from among multiple random access preambles, and the multiple random access preambles correspond to a receiving window of a random access response; and the terminal device determining, according to the transmission power of a first random access preamble from among the at least one random access preamble, the power for sending a physical uplink shared channel (PUSCH).