The tetra-tert-butylnaphthalocyaninagallium iodine ((t-Bu)4NcGaI) was synthesized. The structure of the compound was tested by elementary analysis, infrared spectrum and hydrogen nuclear magnetic resonance spectrum. Q band of the compound is in the near infrared region (801 nm), red shift about 70 nm compared with phthalocyanine. Z-scan curve of dichlromethane solution of the compound with the concentration of 1.22×104 mol/L was tested by using a frequency-doubled Q-switched Nd:YAG laser with 4.5 ns laser pulse, repeated frequency of 2 Hz and pulse energy of 39.8 μJ at the wavelength of 532 nm. The nonlinear refracting index, n2 and the third-order nonlinear polarizability, χ(3) were 2.54×10-11 esu and 9.51×10-12 esu, respectively, so the molecular polarizability γ′ of the compound was 3.3×10-29 esu.