The invention discloses a distributed adjustment method for a node initial back-off window when an unlicensed frequency band is shared by LTE and WiFi. The LTE base station and the WiFi node share anunlicensed frequency band; the WiFi nodes comprise a WiFi wireless access point and a WiFi user node; the WiFi node accesses a channel by using a CSMA/CA protocol; and the LTE base station accesses the channel by using an LBT and backoff mechanism, and the LTE base station and the WiFi node adjust respective initial backoff window sizes in a distributed manner according to respective observed information so as to maximize the throughput of the LTE and WiFi coexisting network under the condition of meeting 3GPP fair limitation.