A scheduling assignment information transmission method for device-to-device communication, the method comprising: obtaining, by a user equipment, a multiplexing manner, wherein the multiplexing manner is used to indicate a relationship between a time-frequency resource for transmitting scheduling assignment information and a time-frequency resource for transmitting data information, wherein the multiplexing manner indicates that a time domain resource for transmitting the scheduling assignment information is the same as a time domain resource for transmitting the data information, and a frequency domain resource for transmitting the scheduling assignment information is not adjacent to a frequency domain resource for transmitting the data information, or the multiplexing manner indicates that a time domain resource for transmitting the scheduling assignment information is the same as a time domain resource for transmitting the data information, and a frequency domain resource for transmitting the scheduling assignment information is adjacent to a frequency domain resource for transmitting the data information; receiving, by the user equipment, downlink control information sent by a network device, wherein the downlink control information comprises scheduling assignment resource indication information; obtaining, by the user equipment based on the scheduling assignment resource indication information and the multiplexing manner, resource location information occupied to transmit the scheduling assignment information; and transmitting, by the user equipment, the scheduling assignment information based on the resource location information occupied by the scheduling assignment information. obtaining, by a user equipment, a multiplexing manner, wherein the multiplexing manner is used to indicate a relationship between a time-frequency resource for transmitting scheduling assignment information and a time-frequency resource for transmitting data information, wherein the multiplexing manner indicates that a time domain resource for transmitting the scheduling assignment information is the same as a time domain resource for transmitting the data information, and a frequency domain resource for transmitting the scheduling assignment information is not adjacent to a frequency domain resource for transmitting the data information, or the multiplexing manner indicates that a time domain resource for transmitting the scheduling assignment information is the same as a time domain resource for transmitting the data information, and a frequency domain resource for transmitting the scheduling assignment information is adjacent to a frequency domain resource for transmitting the data information; receiving, by the user equipment, downlink control information sent by a network device, wherein the downlink control information comprises scheduling assignment resource indication information; obtaining, by the user equipment based on the scheduling assignment resource indication information and the multiplexing manner, resource location information occupied to transmit the scheduling assignment information; and transmitting, by the user equipment, the scheduling assignment information based on the resource location information occupied by the scheduling assignment information.