A power control method, comprising: sending, by a first terminal device, first data and first sidelink control information corresponding to the first data to at least one second terminal device (2, 3, 4); receiving, by the first terminal device, at least one piece of power adjustment information from the at least one second terminal device (2, 3, 4), wherein the at least one piece of power adjustment information is determined by the at least one second terminal device (2, 3, 4) based on at least one of the first data and the first sidelink control information, wherein the at least one piece of power adjustment information is determined based on power indication information sent by the first terminal device, wherein the power indication information is comprised in the first data or comprised in the first sidelink control information, and wherein the power indication information is used to indicate a first transmit power for at least one of the first data and the first sidelink control information; receiving, by the first terminal device, a path loss-related parameter from the at least one second terminal device (2, 3, 4), wherein the path loss-related parameter is an actual transmit power of the at least one second terminal device (2, 3, 4), determining, by the first terminal device, a second transmit power for second data based on the at least one piece of power adjustment information and the path loss-related parameter, wherein a first power adjustment value is determined based on a value of the at least one piece of power adjustment information, and wherein the second transmit power for the second data satisfies following formula: P PSSCH = min P CMAX, PSSCH, 10 log 10 M PSSCH + P O_PSSCH + α PSSCH ⋅ PL + δ PSSCH, where P PSSCH is the second transmit power for the second data, P CMAX, PSSCH is a maximum transmit power of the first terminal device, M PSSCH is a quantity of physical resource blocks occupied by the first terminal device to send the second data, PL is a path loss estimated by the first terminal device, P O_SSCH and α PSSCH are higher layer parameters, δ PSSCH is the first power adjustment value; and sending, by the first terminal device, the second data to the at least one second terminal device (2, 3, 4) at the second transmit power. sending, by a first terminal device, first data and first sidelink control information corresponding to the first data to at least one second terminal device (2, 3, 4); receiving, by the first terminal device, at least one piece of power adjustment information from the at least one second terminal device (2, 3, 4), wherein the at least one piece of power adjustment information is determined by the at least one second terminal device (2, 3, 4) based on at least one of the first data and the first sidelink control information, wherein the at least one piece of power adjustment information is determined based on power indication information sent by the first terminal device, wherein the power indication information is comprised in the first data or comprised in the first sidelink control information, and wherein the power indication information is used to indicate a first transmit power for at least one of the first data and the first sidelink control information; receiving, by the first terminal device, a path loss-related parameter from the at least one second terminal device (2, 3, 4), wherein the path loss-related parameter is an actual transmit power of the at least one second terminal device (2, 3, 4), determining, by the first terminal device, a second transmit power for second data based on the at least one piece of power adjustment information and the path loss-related parameter, wherein a first power adjustment value is determined based on a value of the at least one piece of power adjustment information, and wherein the second transmit power for the second data satisfies following formula: P PSSCH = min P CMAX, PSSCH, 10 log 10 M PSSCH + P O_PSSCH + α PSSCH ⋅ PL + δ PSSCH, where P PSSCH is the second transmit power for the second data, P CMAX, PSSCH is a maximum transmit power of the first terminal device, M PSSCH is a quantity of physical resource blocks occupied by the first terminal device to send the second data, PL is a path loss estimated by the first terminal device, P O_SSCH and α PSSCH are higher layer parameters, δ PSSCH is the first power adjustment value; and sending, by the first terminal device, the second data to the at least one second terminal device (2, 3, 4) at the second transmit power. P PSSCH is the second transmit power for the second data, P CMAX, PSSCH is a maximum transmit power of the first terminal device, M PSSCH is a quantity of physical resource blocks occupied by the first terminal device to send the second data, PL is a path loss estimated by the first terminal device, P O_SSCH and α PSSCH are higher layer parameters, δ PSSCH is the first power adjustment value; and sending, by the first terminal device, the second data to the at least one second terminal device (2, 3, 4) at the second transmit power.