1. A method of extracting a sound source acoustic image body in 3D space, the method comprises: step 1, determining a spatial position of a sound source acoustic image, which is achieved by: processing time-frequency conversion for a signal of each channel and processing the same sub-band division for each channel; and with the listener as a spherical coordinate system origin, for a speaker with the horizontal angle μ i and elevation angle η i , setting a vector p i (k,n) re presenting the time-frequency representation of the corresponding signal, p i ( k , n ) = g i ( k , n ) · [ cos μ i · cos η i sin μ i · cos η i sin η i ] wherein i refers to an index value of the speaker, k refers to a frequency band index, n refers to a time domain frame number index, g i (k,n) refers to a intensity information of a frequency domain point; the horizontal angle μ i and elevation angle η i is calculated using the following formula, tan μ ( k , n ) = ∑ i = 1 N g i ( k , n ) · cos μ i · cos η i ∑ i = 1 N g i ( k , n ) · sin μ i · cos η i tan η ( k , n ) = [ ∑ i = 1 N g i ( k , n ) · cos μ i · cos η i ] 2 + [ ∑ i = 1 N g i ( k , n ) · sin μ i · cos η i ] 2 ∑ i = 1 N g i ( k , n ) · sin η i wherein, N refers to a total number of the speakers, i values for 1,2. .. N, μ (k, n), η (k, n) i.e., the horizontal angle μ and elevation angle η of the sound source acoustic image in k-th frequency band of the n-th frame; a distance ρ from the sound source acoustic image audio to the origin of the spherical coordinate system takes the average distance of distances from all the speakers to the listener; step 2, determining the speaker beside the spatial position where the sound source acoustic image is located according to the determined spatial position (ρ, μ, η) of the sound source acoustic image; step 3, calculating a correlation of signals of all sound tracks of the speakers selected at step 2 in the horizontal direction and the vertical direction, which is achieved by: dividing the selected speakers into left part and right part according to the location of the acoustic image, using the vertical plane of the connecting line between the sound source acoustic image and the listener as a projection plane, calculating a sum of the components of the left and right signals which are perpendicular to the projection plane respectively, denoting the sums as P L and P R respectively, and calculating the correlation IC H of the left and right signals as follows, IC H = cov ( P L , P R ) cov ( P L , P L ) · cov ( P R , P R ) dividing the selected speakers into upper part and lower part according to the location of the acoustic image, using a plane where the sound source acoustic image and the listener are located as a projection plane, calculating a sum of the components of the upper and lower signals which are perpendicular to the projection plane respectively, denoting the sums as P U and P D respectively, and calculating the correlation IC v of the upper and lower signals as follows, IC V = cov ( P U , P D ) cov ( P U , P U ) · cov ( P D , P D ) step 4, obtaining and storing a parameter set {IC H , IC v , Min{IC H , IC v }} of the acoustic image body, wherein the Min{IC H , IC v } is a smaller value between IC H and IC v .