A method for preparing phthalocyanine nanospheres is provided, including: synthesizing an ionic phthalocyanine molecule of formula I according to a following chemical scheme: wherein M is Cu or Zn, X is Br or Cl, R1, R2, R3, and R4 are aromatic substituent groups; dissolving at least one ionic phthalocyanine molecule selected from the formula I in a solvent to form a solution; preparing a two-dimensional layer crystalline material with an opposite charge to the ionic phthalocyanine molecule; adding the two-dimensional layer crystalline material to the solution; heating the solution to evaporate a portion of the solvent to aggregate the ionic phthalocyanine molecule into phthalocyanine nanospheres between a film layer of the two-dimensional layer crystalline material; and separating the phthalocyanine nanospheres from the film layer of the two-dimensional layer crystalline material.