The invention discloses a method for selectively exciting diffraction levels on the basis of metasurface complex amplitude modulation, and belongs to the field of micro-nano optics. The structure sizes of nano rectangular columns of metasurfaces are changed to obtain amplitudes and dynamic phase information of target light fields, and azimuth angles theta of the nano rectangular columns of the metasurfaces are determined, and accordingly phases of the target light fields can be modulated; the amplitudes and the phase information are combined with one another, and accordingly complex amplitudescan be arbitrarily regulated and controlled in a single pixel; the periods of the metasurfaces are determined, Fourier levels corresponding to all the selected diffraction levels are superimposed, accordingly, complex amplitude information of various unit structures of the metasurfaces can be set, and the spatial propagation diffraction levels can be selectively excited. The method has the advantages that amplitude values of the target light fields can be processed by stages, and the phases of the target light fields can be continuously changed; the metasurface design and processing complexity can be lowered by the aid of the method, and the method can be widely applied to the fields of light field shaping, laser parallel processing, micro-nano optical detection and the like.