A method for adaptively adjusting uplink and downlink bandwidth, comprising: a base station determining a usage status of the uplink and downlink bandwidth in a preset time, and obtaining a bandwidth amount Δ BW DL required to be adjusted of downlink bandwidth and a bandwidth amount Δ BW UL required to be adjusted of uplink bandwidth; when Δ BW DL is less than 0, Δ BW UL is greater than 0, an absolute value of Δ BW DL is less than or equal to an absolute value of Δ BW UL, and the absolute value of Δ BW DL is greater than or equal to a certain element in a preset resource block, RB, number set which can be adjusted, the base station selecting a maximum value less than the absolute value of Δ BW DL from the RB number set which can be adjusted as adjustment bandwidth to allocate to the downlink bandwidth borrowed from the uplink; when Δ BW UL is less than 0, Δ BW DL is greater than 0, the absolute value of Δ BW UL is less than or equal to the absolute value of Δ BW DL, and the absolute value of Δ BW UL is greater than or equal to a certain element in the RB number set which can be adjusted, the base station selecting the maximum value less than the absolute value of Δ BW UL from the RB number set which can be adjusted as the adjustment bandwidth to allocate to the uplink bandwidth borrowed from the downlink; the base station sending information to a terminal, indicating whether bandwidth from the downlink is borrowed by the uplink or bandwidth from the uplink is borrowed by the downlink through spare ten bits in a logical channel message corresponding to a Physical Broadcast Channel, PBCH, characterized by the base station further sending information to the terminal, indicating an amount and a location of borrowing bandwidth through the spare ten bits in the logical channel message corresponding to the PBCH. a base station determining a usage status of the uplink and downlink bandwidth in a preset time, and obtaining a bandwidth amount Δ BW DL required to be adjusted of downlink bandwidth and a bandwidth amount Δ BW UL required to be adjusted of uplink bandwidth; when Δ BW DL is less than 0, Δ BW UL is greater than 0, an absolute value of Δ BW DL is less than or equal to an absolute value of Δ BW UL, and the absolute value of Δ BW DL is greater than or equal to a certain element in a preset resource block, RB, number set which can be adjusted, the base station selecting a maximum value less than the absolute value of Δ BW DL from the RB number set which can be adjusted as adjustment bandwidth to allocate to the downlink bandwidth borrowed from the uplink; when Δ BW UL is less than 0, Δ BW DL is greater than 0, the absolute value of Δ BW UL is less than or equal to the absolute value of Δ BW DL, and the absolute value of Δ BW UL is greater than or equal to a certain element in the RB number set which can be adjusted, the base station selecting the maximum value less than the absolute value of Δ BW UL from the RB number set which can be adjusted as the adjustment bandwidth to allocate to the uplink bandwidth borrowed from the downlink; the base station sending information to a terminal, indicating whether bandwidth from the downlink is borrowed by the uplink or bandwidth from the uplink is borrowed by the downlink through spare ten bits in a logical channel message corresponding to a Physical Broadcast Channel, PBCH, characterized by the base station further sending information to the terminal, indicating an amount and a location of borrowing bandwidth through the spare ten bits in the logical channel message corresponding to the PBCH.