Method for sending lead code, method and terminal for realizing downlink synchronization

The invention discloses a method for sending a lead code, a method and a terminal for realizing downlink synchronization. The method for realizing the downlink synchronization comprises the following steps: receiving the lead code from a base station by the terminal, wherein the lead code comprises a main lead code carrying community type information and an auxiliary lead code carrying community/sector identification information; acquiring the main lead code on preset band width by the terminal; and acquiring the auxiliary lead code through the acquired main lead code and realizing the downlink synchronization with the base station according to the main lead code and the auxiliary lead code by the terminal. The invention can meet the need of a 802.16 m system on community identification and realize the fast downlink synchronization.