Abstract: A second harmonic generation (SHG) measurement system for organic powders have been built.Then the second order nonlinear optical properties of acridine derivates have been measured with this experimental setup and compared with the calculated value obtained by the solvatochromic method.The intensity of second harmonic generation of acridine derivate microcrystal was related to its structure and molecular refractive index.Acridines with two dimension dipole "Λ" type structure,intermolecular hydrogen bond,long chain alkyl with branches and methyl group possess high nonlinear optical properties.The relative SHG of these microcrystals were proportional to their hypersusceptibilities,but not comformed to the Kurtz Perry relation.