A method for indicating a slot format, comprising: sending, by a network device, a slot format indicator, SFI, to a terminal, wherein the SFI is used to indicate a slot format of at least one carrier, the at least one carrier comprises a first carrier, the slot format indicated by the SFI is determined based on a first subcarrier spacing and a subcarrier spacing of the first carrier is X multiple of the first subcarrier spacing, X being a positive integer, wherein the first subcarrier spacing is configured by radio resource control, RRC, signaling; wherein each slot format indicated by the SFI is used to determine slot formats of X slots of the first carrier; wherein the SFI comprises a slot format index, wherein the slot format index is used to indicate the slot format of the at least one carrier, and the slot format index is sent in a field corresponding the carrier for which the slot format is indicated; wherein the at least one carrier further comprises a second carrier, wherein a subcarrier spacing of the second carrier is equal to the first subcarrier spacing, and each slot format indicated by the SFI is used to determine a slot format of one slot of the second carrier; wherein a start time of an the i th slot indicated by the SFI on the second carrier is the same as a start time of an [(i-1) ∗ X+1] th slot indicated by the SFI on the first carrier, an end time of the i th slot indicated by the SFI on the second carrier is the same as an end time of an (i ∗ X) th slot indicated by the SFI on the first carrier, and the slot formats of the [(i-1) ∗ X+1] th slot to the (i*X) th slot indicated by the SFI on the first carrier are the same, i being a positive integer. sending, by a network device, a slot format indicator, SFI, to a terminal, wherein the SFI is used to indicate a slot format of at least one carrier, the at least one carrier comprises a first carrier, the slot format indicated by the SFI is determined based on a first subcarrier spacing and a subcarrier spacing of the first carrier is X multiple of the first subcarrier spacing, X being a positive integer, wherein the first subcarrier spacing is configured by radio resource control, RRC, signaling; wherein each slot format indicated by the SFI is used to determine slot formats of X slots of the first carrier; wherein the SFI comprises a slot format index, wherein the slot format index is used to indicate the slot format of the at least one carrier, and the slot format index is sent in a field corresponding the carrier for which the slot format is indicated; wherein the at least one carrier further comprises a second carrier, wherein a subcarrier spacing of the second carrier is equal to the first subcarrier spacing, and each slot format indicated by the SFI is used to determine a slot format of one slot of the second carrier; wherein a start time of an the i th slot indicated by the SFI on the second carrier is the same as a start time of an [(i-1) ∗ X+1] th slot indicated by the SFI on the first carrier, an end time of the i th slot indicated by the SFI on the second carrier is the same as an end time of an (i ∗ X) th slot indicated by the SFI on the first carrier, and the slot formats of the [(i-1) ∗ X+1] th slot to the (i*X) th slot indicated by the SFI on the first carrier are the same, i being a positive integer.