This application discloses a communication method and a communications apparatus. The method includes: determining, by a terminal device, transmission power for sending a random access preamble, where the transmission power is related to a random access preamble format and an offset based on the random access preamble format; and sending, by the terminal device, the random access preamble at the determined transmission power. The random access preamble format includes some or all of 0 to 3, A0 to A3, B1 to B4, C0, and C2. The corresponding apparatus is further disclosed. In this application, offsets corresponding to a plurality of random access preamble formats in a next-generation mobile communications system are provided, so that the transmission power of the random access preamble can be properly determined.