A communications apparatus (400, 500), comprising a processing unit (41, 52) and a sending unit (42, 53), wherein: the processing unit (41, 52) is configured to determine transmission power for sending a random access preamble, wherein the transmission power is related to an offset based on a random access preamble format; and the sending unit (42, 53) is configured to send the random access preamble at the transmission power; wherein the random access preamble format is one of formats A1, A2, A3, B1, B2, B3, B4, C0 and C2, and the offset based on the random access preamble format is respectively X-3 dB, X-6 dB, X-8 dB, X-3 dB, X-6 dB, X-8 dB, X-11 dB, X+0 dB, or X-6 dB, wherein X is an integer or a decimal, and a value of X is associated with a carrier frequency; wherein the processing unit (41, 52) is specifically configured to: determine that the transmission power is a smaller value in the following two values: maximum transmission power allowed by or configured for a terminal device, and a sum of random access preamble target received power, beam-related offset G and a path loss that is estimated by the terminal device; wherein the random access preamble target received power is a sum of the following three parameters: random access preamble initial received target power, the offset based on the random access preamble format, and a product of a quantity of power ramping times minus 1 and a power ramping step; wherein the beam-related offset G satisfies G = round(-10 × log 10 N b) and N b is a quantity of beams of the network device for receiving the random access preamble, wherein N b is 1, 2, 3 or 4 and round represents round off, round down or round up to the nearest integer. the processing unit (41, 52) is configured to determine transmission power for sending a random access preamble, wherein the transmission power is related to an offset based on a random access preamble format; and the sending unit (42, 53) is configured to send the random access preamble at the transmission power; wherein the random access preamble format is one of formats A1, A2, A3, B1, B2, B3, B4, C0 and C2, and the offset based on the random access preamble format is respectively X-3 dB, X-6 dB, X-8 dB, X-3 dB, X-6 dB, X-8 dB, X-11 dB, X+0 dB, or X-6 dB, wherein X is an integer or a decimal, and a value of X is associated with a carrier frequency; wherein the processing unit (41, 52) is specifically configured to: determine that the transmission power is a smaller value in the following two values: maximum transmission power allowed by or configured for a terminal device, and a sum of random access preamble target received power, beam-related offset G and a path loss that is estimated by the terminal device; wherein the random access preamble target received power is a sum of the following three parameters: random access preamble initial received target power, the offset based on the random access preamble format, and a product of a quantity of power ramping times minus 1 and a power ramping step; wherein the beam-related offset G satisfies G = round(-10 × log 10 N b) and N b is a quantity of beams of the network device for receiving the random access preamble, wherein N b is 1, 2, 3 or 4 and round represents round off, round down or round up to the nearest integer. determine that the transmission power is a smaller value in the following two values: maximum transmission power allowed by or configured for a terminal device, and a sum of random access preamble target received power, beam-related offset G and a path loss that is estimated by the terminal device; wherein the random access preamble target received power is a sum of the following three parameters: random access preamble initial received target power, the offset based on the random access preamble format, and a product of a quantity of power ramping times minus 1 and a power ramping step; wherein the beam-related offset G satisfies G = round(-10 × log 10 N b) and N b is a quantity of beams of the network device for receiving the random access preamble, wherein N b is 1, 2, 3 or 4 and round represents round off, round down or round up to the nearest integer.