A switch assembly, a switch assembly control method, a controller, and a base station are disclosed, which relate to the wireless communications field. The switch assembly includes: a mechanical normally open switch (102), a movable contact (104), and a controller (106), where the controller (106) is connected to a phase shifter (108) of a remote electrical tilt unit, and the movable contact (104) is arranged to move with a driving rod (1082) of the phase shifter (108); when the movable contact (104) reaches a specified position, the mechanical normally open switch (102) is triggered to close. A prior-art problem that interference is caused to a base station signal because an integrated semiconductor chip radio frequency switch is a nonlinear element and a problem that installation is relatively difficult because a volume of a relay switch is relatively large are resolved.