A preamble sequence sending method, comprising: sending, by user equipment, UE, a first preamble sequence according to a first transmit power and by using a repetition factor N 1; if the UE fails to receive, in a preset time period after the first preamble sequence is sent, a response message that is sent by a network-side device and that is corresponding to the first preamble sequence, switching, by the UE, to a next repetition factor N 2, wherein a quantity of consecutive sending times indicated by the next repetition factor N 2 is greater than a quantity of consecutive sending times indicated by the repetition factor N 1; and sending, by the UE, a second preamble sequence according to a second transmit power and by using the next repetition factor N 2, wherein when the repetition factor N 1 is an initial repetition factor, before the sending, by the UE, of the first preamble sequence according to the first transmit power and by using the repetition factor N 1, the method being characterized by: determining, by the UE, preamble sequence powers separately corresponding to a first repetition factor and a second repetition factor; and determining that the first repetition factor is the repetition factor N 1 when the preamble sequence power corresponding to the first repetition factor is less than or equal to a difference between a maximum permissible transmit power of the UE and a specific constant and the preamble sequence power corresponding to the second repetition factor is greater than the difference between the maximum permissible transmit power of the UE and the specific constant, or when the preamble sequence power corresponding to the first repetition factor is less than the difference between the maximum permissible transmit power of the UE and the specific constant and the preamble sequence power corresponding to the second repetition factor is greater than or equal to the difference between the maximum permissible transmit power of the UE and the specific constant, wherein the second repetition factor is less than the first repetition factor and is adjacent to the first repetition factor among repetition factors. sending, by user equipment, UE, a first preamble sequence according to a first transmit power and by using a repetition factor N 1; if the UE fails to receive, in a preset time period after the first preamble sequence is sent, a response message that is sent by a network-side device and that is corresponding to the first preamble sequence, switching, by the UE, to a next repetition factor N 2, wherein a quantity of consecutive sending times indicated by the next repetition factor N 2 is greater than a quantity of consecutive sending times indicated by the repetition factor N 1; and sending, by the UE, a second preamble sequence according to a second transmit power and by using the next repetition factor N 2, wherein when the repetition factor N 1 is an initial repetition factor, before the sending, by the UE, of the first preamble sequence according to the first transmit power and by using the repetition factor N 1, the method being characterized by: determining, by the UE, preamble sequence powers separately corresponding to a first repetition factor and a second repetition factor; and determining that the first repetition factor is the repetition factor N 1 when the preamble sequence power corresponding to the first repetition factor is less than or equal to a difference between a maximum permissible transmit power of the UE and a specific constant and the preamble sequence power corresponding to the second repetition factor is greater than the difference between the maximum permissible transmit power of the UE and the specific constant, or when the preamble sequence power corresponding to the first repetition factor is less than the difference between the maximum permissible transmit power of the UE and the specific constant and the preamble sequence power corresponding to the second repetition factor is greater than or equal to the difference between the maximum permissible transmit power of the UE and the specific constant, wherein the second repetition factor is less than the first repetition factor and is adjacent to the first repetition factor among repetition factors. determining, by the UE, preamble sequence powers separately corresponding to a first repetition factor and a second repetition factor; and determining that the first repetition factor is the repetition factor N 1 when the preamble sequence power corresponding to the first repetition factor is less than or equal to a difference between a maximum permissible transmit power of the UE and a specific constant and the preamble sequence power corresponding to the second repetition factor is greater than the difference between the maximum permissible transmit power of the UE and the specific constant, or when the preamble sequence power corresponding to the first repetition factor is less than the difference between the maximum permissible transmit power of the UE and the specific constant and the preamble sequence power corresponding to the second repetition factor is greater than or equal to the difference between the maximum permissible transmit power of the UE and the specific constant, wherein the second repetition factor is less than the first repetition factor and is adjacent to the first repetition factor among repetition factors.