The present invention discloses a method for adaptively adjusting uplink and downlink bandwidth, which includes: a base station counting a usage status of the uplink and downlink bandwidth in a preset time, and obtaining a bandwidth amount ΔBWDL required to be coordinated of downlink bandwidth and a bandwidth amount ΔBWUL required to be coordinated of uplink bandwidth; the base station determining a direction, amount and location of the required change of the uplink and downlink bandwidth according to the obtained ΔBWDL and ΔBWUL ; the base station carrying the determined direction, amount and location of the required change of the uplink and downlink bandwidth through residual ten bits in a logical channel message corresponding to a Physical Broadcast Channel (PBCH) and informing a terminal of the direction, amount and location. The present invention also discloses a device for adaptively adjusting the uplink and downlink bandwidth.