A data transmission method, comprising: obtaining, by user equipment UE, a maximum transmit power; determining, by the UE, a transmit power of a data channel and a transmit power of a control channel based on the maximum transmit power and a first parameter, wherein the first parameter comprises a bandwidth of the data channel and a bandwidth of the control channel; wherein the determining, by the UE, a transmit power of a data channel and a transmit power of a control channel based on the maximum transmit power and a first parameter comprises: determining whether a first power is greater than the maximum transmit power, wherein the first power equals 10 log 10 M PSSCH + 10 c 10 × M PSCCH + P O_PSSCH + α PSSCH ⋅ PL wherein M PSSCH indicates the bandwidth of the data channel and M PSCCH indicates the bandwidth of a control channel, PL indicates a value of the path loss between the apparatus and a base station, α PSSCH indicates a path loss compensation coefficient of the data channel, P O_PSSCH indicates a power parameter value configured by the base station or a predefined power parameter value, and c is a predefined constant, when the first power is greater than the maximum transmit power; determining the transmit power of the data channel based on a sum of the maximum transmit power and a first additional item, wherein the first additional item is determined based on M PSSCH and M PSCCH; determining the transmit power of the control channel based on a sum of the maximum transmit power and a second additional item, wherein the second additional item is determined based on M PSSCH and M PSCCH; and sending, by the UE, the control channel and the data channel in a same subframe. obtaining, by user equipment UE, a maximum transmit power; determining, by the UE, a transmit power of a data channel and a transmit power of a control channel based on the maximum transmit power and a first parameter, wherein the first parameter comprises a bandwidth of the data channel and a bandwidth of the control channel; wherein the determining, by the UE, a transmit power of a data channel and a transmit power of a control channel based on the maximum transmit power and a first parameter comprises: determining whether a first power is greater than the maximum transmit power, wherein the first power equals 10 log 10 M PSSCH + 10 c 10 × M PSCCH + P O_PSSCH + α PSSCH ⋅ PL wherein M PSSCH indicates the bandwidth of the data channel and M PSCCH indicates the bandwidth of a control channel, PL indicates a value of the path loss between the apparatus and a base station, α PSSCH indicates a path loss compensation coefficient of the data channel, P O_PSSCH indicates a power parameter value configured by the base station or a predefined power parameter value, and c is a predefined constant, when the first power is greater than the maximum transmit power; determining the transmit power of the data channel based on a sum of the maximum transmit power and a first additional item, wherein the first additional item is determined based on M PSSCH and M PSCCH; determining the transmit power of the control channel based on a sum of the maximum transmit power and a second additional item, wherein the second additional item is determined based on M PSSCH and M PSCCH; and sending, by the UE, the control channel and the data channel in a same subframe. determining whether a first power is greater than the maximum transmit power, wherein the first power equals 10 log 10 M PSSCH + 10 c 10 × M PSCCH + P O_PSSCH + α PSSCH ⋅ PL wherein M PSSCH indicates the bandwidth of the data channel and M PSCCH indicates the bandwidth of a control channel, PL indicates a value of the path loss between the apparatus and a base station, α PSSCH indicates a path loss compensation coefficient of the data channel, P O_PSSCH indicates a power parameter value configured by the base station or a predefined power parameter value, and c is a predefined constant, when the first power is greater than the maximum transmit power; wherein M PSSCH indicates the bandwidth of the data channel and M PSCCH indicates the bandwidth of a control channel, PL indicates a value of the path loss between the apparatus and a base station, α PSSCH indicates a path loss compensation coefficient of the data channel, P O_PSSCH indicates a power parameter value configured by the base station or a predefined power parameter value, and c is a predefined constant, when the first power is greater than the maximum transmit power; determining the transmit power of the data channel based on a sum of the maximum transmit power and a first additional item, wherein the first additional item is determined based on M PSSCH and M PSCCH; determining the transmit power of the control channel based on a sum of the maximum transmit power and a second additional item, wherein the second additional item is determined based on M PSSCH and M PSCCH; and sending, by the UE, the control channel and the data channel in a same subframe. the second additional item is determined based on M PSSCH and M PSCCH; and sending, by the UE, the control channel and the data channel in a same subframe.