A bandwidth adjustment method, comprising: adjusting a bandwidth of a channel of a first network system and a bandwidth of a channel of a second network system adjacent to a guard bandwidth based on a user request or a channel condition; and determining a bandwidth update value of the channel of the first network system, a bandwidth update value of the channel of the second network system and a bandwidth update value of the guard bandwidth, wherein a guard interval with the guard bandwidth is arranged between the bandwidth of the channel of the first network system and the bandwidth of the channel of the second network system, and an updated bandwidth of the channel of the first network system and an updated bandwidth of the channel of the second network system meet the user request or a requirement of the channel condition; and transmitting the bandwidth update value of the channel of the first network system to the first network system and transmitting the bandwidth update value of the channel of the second network system to the second network system, wherein the first network system adjusts the bandwidth of the channel of the first network system based on the bandwidth update value of the channel of the first network system, and the second network system adjusts the bandwidth of the channel of the second network system based on the bandwidth update value of the channel of the second network system, and wherein the bandwidth update value of the guard bandwidth further meets the following relation: GB n,11 = g BW n,1, BW n,2, wherein GB n,1l is the bandwidth update value of the guard bandwidth, BW n,1 is the bandwidth update value of the channel of the first network system, BW n,2 is the bandwidth update value of the channel of the second network system, and GB n,1l = g(BW n,1, BW n,2) is a function increasing with an increase of any one of BW n,1 and BW n,2. adjusting a bandwidth of a channel of a first network system and a bandwidth of a channel of a second network system adjacent to a guard bandwidth based on a user request or a channel condition; and determining a bandwidth update value of the channel of the first network system, a bandwidth update value of the channel of the second network system and a bandwidth update value of the guard bandwidth, wherein a guard interval with the guard bandwidth is arranged between the bandwidth of the channel of the first network system and the bandwidth of the channel of the second network system, and an updated bandwidth of the channel of the first network system and an updated bandwidth of the channel of the second network system meet the user request or a requirement of the channel condition; and transmitting the bandwidth update value of the channel of the first network system to the first network system and transmitting the bandwidth update value of the channel of the second network system to the second network system, wherein the first network system adjusts the bandwidth of the channel of the first network system based on the bandwidth update value of the channel of the first network system, and the second network system adjusts the bandwidth of the channel of the second network system based on the bandwidth update value of the channel of the second network system, and wherein the bandwidth update value of the guard bandwidth further meets the following relation: GB n,11 = g BW n,1, BW n,2, wherein GB n,1l is the bandwidth update value of the guard bandwidth, BW n,1 is the bandwidth update value of the channel of the first network system, BW n,2 is the bandwidth update value of the channel of the second network system, and GB n,1l = g(BW n,1, BW n,2) is a function increasing with an increase of any one of BW n,1 and BW n,2.