A method for transmitting downlink data, characterized in that, the method comprises: obtaining, by a base station, a pre-coding matrix of a UE, and an l -th level of group of pre-coding matrixes among L groups of pre-coding matrixes corresponding to the pre-coding matrix, wherein each of the L groups of pre-coding matrixes comprises at least one pre-coding matrix from a preset codebook, l ≤ L, L and l are positive integers and each of the L groups of pre-coding matrixes corresponds to a piece of moving speed information respectively, wherein for the moving speed information corresponding to any one of the L groups of pre-coding matrixes, a signal to noise ratio of the UE receiving the downlink data using the any one of the L groups of pre-coding matrixes while moving at a corresponding moving speed corresponding to the moving speed information is greater than or equal to a preset threshold; wherein obtaining, by the base station, the l -th level of group of pre-coding matrixes among the L groups of pre-coding matrixes corresponding to the pre-coding matrix comprises: obtaining, by the base station, the l -th level of group of pre-coding matrixes corresponding to current moving speed of the UE, according to a correspondence relationship between moving speed information, a pre-coding matrix, and a level index of a group of pre-coding matrixes; and transmitting, by the base station, downlink data to the UE according to the pre-coding matrixes in the l -th level of group of pre-coding matrixes; wherein any one of the pre-coding matrixes in the codebook corresponds to L groups of pre-coding matrixes, the l -th level of group of pre-coding matrixes among the L groups of pre-coding matrixes comprises N l pre-coding matrixes, the N l pre-coding matrixes are first N l pre-coding matrixes in the codebook comprising the pre-coding matrixes sorted in an ascending order of their distances from the any one pre-coding matrix, or the N l pre-coding matrixes are first N l pre-coding matrixes in the codebook comprising the pre-coding matrixes sorted in an ascending order of their distances from a vector corresponding to a normal of an antennas array of the base station, N l < N l +1, N l and N l +1 are positive integers. obtaining, by a base station, a pre-coding matrix of a UE, and an l -th level of group of pre-coding matrixes among L groups of pre-coding matrixes corresponding to the pre-coding matrix, wherein each of the L groups of pre-coding matrixes comprises at least one pre-coding matrix from a preset codebook, l ≤ L, L and l are positive integers and each of the L groups of pre-coding matrixes corresponds to a piece of moving speed information respectively, wherein for the moving speed information corresponding to any one of the L groups of pre-coding matrixes, a signal to noise ratio of the UE receiving the downlink data using the any one of the L groups of pre-coding matrixes while moving at a corresponding moving speed corresponding to the moving speed information is greater than or equal to a preset threshold; wherein obtaining, by the base station, the l -th level of group of pre-coding matrixes among the L groups of pre-coding matrixes corresponding to the pre-coding matrix comprises: obtaining, by the base station, the l -th level of group of pre-coding matrixes corresponding to current moving speed of the UE, according to a correspondence relationship between moving speed information, a pre-coding matrix, and a level index of a group of pre-coding matrixes; and transmitting, by the base station, downlink data to the UE according to the pre-coding matrixes in the l -th level of group of pre-coding matrixes; wherein any one of the pre-coding matrixes in the codebook corresponds to L groups of pre-coding matrixes, the l -th level of group of pre-coding matrixes among the L groups of pre-coding matrixes comprises N l pre-coding matrixes, the N l pre-coding matrixes are first N l pre-coding matrixes in the codebook comprising the pre-coding matrixes sorted in an ascending order of their distances from the any one pre-coding matrix, or the N l pre-coding matrixes are first N l pre-coding matrixes in the codebook comprising the pre-coding matrixes sorted in an ascending order of their distances from a vector corresponding to a normal of an antennas array of the base station, N l < N l +1, N l and N l +1 are positive integers. obtaining, by the base station, the l -th level of group of pre-coding matrixes corresponding to current moving speed of the UE, according to a correspondence relationship between moving speed information, a pre-coding matrix, and a level index of a group of pre-coding matrixes; and transmitting, by the base station, downlink data to the UE according to the pre-coding matrixes in the l -th level of group of pre-coding matrixes; wherein any one of the pre-coding matrixes in the codebook corresponds to L groups of pre-coding matrixes, the l -th level of group of pre-coding matrixes among the L groups of pre-coding matrixes comprises N l pre-coding matrixes, the N l pre-coding matrixes are first N l pre-coding matrixes in the codebook comprising the pre-coding matrixes sorted in an ascending order of their distances from the any one pre-coding matrix, or the N l pre-coding matrixes are first N l pre-coding matrixes in the codebook comprising the pre-coding matrixes sorted in an ascending order of their distances from a vector corresponding to a normal of an antennas array of the base station, N l < N l +1, N l and N l +1 are positive integers.