The present invention relates to a method and an apparatus for quantizing channel state information (CSI). According to an embodiment of the present invention, a method for quantizing CSI is provided, which can be implemented on a base station side. The method includes: broadcasting antenna configuration of a base station to a user equipment, wherein the antenna configuration includes an antenna port in a vertical direction and an antenna port in a horizontal direction; sending a reference signal (RS) to the user equipment; receiving a vertical precoder corresponding to the antenna port in a vertical direction and a horizontal precoder corresponding to the antenna port in a horizontal direction that are fed back by the user equipment; and based on the received vertical precoder and horizontal precoder, reconstructing a precoder by using a vertical codebook corresponding to the antenna port in a vertical direction and a horizontal codebook corresponding to the antenna port in a horizontal direction.