Four amino cobalt phthalocyanine is well known as a promising photosensitizer. In order to enrich and complete the theoretical system of structural properties and reactivity, four amino cobalt phthalocyanine was synthesized and its ultraviolet-visible spectrum was obtained by experimental research. Then the experimental spectrum was compared with that obtained from theoretical calculation by quantum chemistry. The experimental results show that there are two obvious absorption peaks at 324.98 and 709.94 nm respectively in the ultraviolet-visible spectrum of four amino cobalt phthalocyanine. The density functional B3LYP/3-21G* method was used in simulating ultraviolet-visible absorption spectra of four amino cobalt phthalocyanine. The calculation results show that there should be two absorption peaks at 321.41 and 709.92 nm respectively. The simulation results agree well with the experimental values, which demonstrates that the density functional theory is valid and reliable in the theoretical research on four amino cobalt phthalocyanine. The contribution rate of various electron transitions in every absorption peak was determined by quantum computation. The contribution rate of various electron transition in every absorption peak was determined by quantum computation. The absorption peak at 326.22 nm is mainly resulted from electronic transition from 152 to 163 LUMO orbit, the absorption peak at 314.42 nm is due to electronic transition from 149 to 164 LUMO+1 orbit, the absorption peak at 747.57 nm is mainly caused by electronic transition from 162 to 163 LUMO orbit, and the absorption peak at 676.01 nm is mainly caused by electronic transition from 162 to 164 LUMO+1 orbit. These data provide great theoretical complement to experimental study. The quantum chemical study for four amino cobalt phthalocyanine ultraviolet-visible spectrum has very important theoretical significance for experimental research in the future.