System information transmission method, base station and user equipment

Provided in embodiments of the present invention are an SI transmission method, a base station and a user equipment. The method comprises: sending a request to a base station, wherein the request is for use in requesting at least one type of SI from a first type of cell, the first type of cell is a cell which requires channel detection prior to sending data; and receiving the at least one type of SI from the first type of cell. In the embodiments of the present invention, the UE requests a system message according to what is needed, thus reducing unnecessary SI costs, and reducing interference of base station to other cells.