A message processing method implemented by a base station, which is applied to a multiuser superposition transmission, MUST, system, comprising: determining a transmission type of information and a transmission parameter corresponding to the transmission type to be sent to a terminal device; and sending a notification message carrying an indication field to the terminal device, wherein the indication field is used to indicate the transmission type and the transmission parameter; and at least one state of the indication field indicates that the transmission type is a first MUST type, and at least one state of the indication field indicates that the transmission type is a third MUST type; wherein when the transmission type indicated by the indication field is the first MUST type, the transmission parameter indicated by the indication field comprises a first power ratio of the terminal device to a paired terminal device; wherein the first power ratio of the terminal device to the paired terminal device comprises a ratio of a power of a first signal sent from the base station to the terminal device on a first spatial layer to a power of a second signal sent from the base station to the paired terminal device on the first spatial layer, wherein powers of signals sent from the base station to the terminal device on the first spatial layer and a second spatial layer are the same; and the base station does not send signals to the paired terminal device on the second spatial layer; wherein the base station allocates a same precoding vector to the terminal device and the paired terminal device when the transmission type indicated by the indication field is the first MUST type; wherein the base station allocates different precoding vectors to the terminal device and the paired terminal device when the transmission type indicated by the indication field is the third MUST type; and wherein values of the indication field jointly encode the transmission type including the first and third MUST types and the transmission parameter including, when the transmission type is the first MUST type, the first power ratio of the terminal device to the paired terminal device, or, when the transmission type is the third MUST type, a second power ratio of the terminal device to the paired terminal device, precoding information of the paired terminal device, or a modulation scheme of the paired terminal device. determining a transmission type of information and a transmission parameter corresponding to the transmission type to be sent to a terminal device; and sending a notification message carrying an indication field to the terminal device, wherein the indication field is used to indicate the transmission type and the transmission parameter; and at least one state of the indication field indicates that the transmission type is a first MUST type, and at least one state of the indication field indicates that the transmission type is a third MUST type; wherein when the transmission type indicated by the indication field is the first MUST type, the transmission parameter indicated by the indication field comprises a first power ratio of the terminal device to a paired terminal device; wherein the first power ratio of the terminal device to the paired terminal device comprises a ratio of a power of a first signal sent from the base station to the terminal device on a first spatial layer to a power of a second signal sent from the base station to the paired terminal device on the first spatial layer, wherein powers of signals sent from the base station to the terminal device on the first spatial layer and a second spatial layer are the same; and the base station does not send signals to the paired terminal device on the second spatial layer; wherein the base station allocates a same precoding vector to the terminal device and the paired terminal device when the transmission type indicated by the indication field is the first MUST type; wherein the base station allocates different precoding vectors to the terminal device and the paired terminal device when the transmission type indicated by the indication field is the third MUST type; and wherein values of the indication field jointly encode the transmission type including the first and third MUST types and the transmission parameter including, when the transmission type is the first MUST type, the first power ratio of the terminal device to the paired terminal device, or, when the transmission type is the third MUST type, a second power ratio of the terminal device to the paired terminal device, precoding information of the paired terminal device, or a modulation scheme of the paired terminal device.