An uplink transmission method and a terminal device, the method including setting, by a terminal device, a first transmit power for a first uplink channel based on a channel priority of the first uplink channel and a channel priority of a first physical random access channel PRACH, where the first uplink channel includes at least one of a physical uplink shared channel PUSCH and a physical uplink control channel PUCCH, a first time domain resource on which the first uplink channel is located and a second time domain resource on which the first PRACH is located overlap, the channel priority of the first uplink channel is higher than or equal to the channel priority of the first PRACH, and the first transmit power is greater than 0, and sending, by the terminal device, the first uplink channel at the first transmit power.