The invention discloses a preparation method for a metal phthalocyanine crystal. The preparation method comprises the following steps: successively adding phthalonitrile and a metal copper sheet into a reaction vessel, then adding an anhydrous ethanol solvent, sealing the reaction vessel, carrying out a solvothermal reaction in a baking oven with a temperature of 180 to 200 DEG C for no less than 3 h, stopping heating after completion of the reaction and carrying out natural cooling to room temperature. A suction pipe is used for meticulous suction of the obtained acicular copper phthalocyanine crystal; then the acicular copper phthalocyanine crystal is soaked and flushed with hot ethanol to remove residual reactants adsorbed on the surface of copper phthalocyanine; and drying is carried out, so purification of the acicular copper phthalocyanine crystal is finished. The method can directly prepare the copper phthalocyanine crystal with regular acicular appearance through one-step reaction without recrystallization. The preparation method is simple to operate, green, pollution-free, and free of production of harmful pollutants; moreover, the method uses the copper sheet as a reactant, so complicated post-treatment during purification caused by usage of a copper salt in the prior art is avoided, the purification process is simple and easily practicable and meets practical production needs.