Three derivatives of alkoxy phthalocyanine Pb were synthesized. The structures of products were characterized by means of infrared (IR), hydrogen nuclear magnetic resonance (HNMR) spectra and elementary analysis. The ultraviolet-visible spectra were measured between 200～800 nm when the derivatives were in polymethyl methacrylate (PMMA) solution. Three derivatives were mixed into PMMA solution independently, then the composite materials which had nonlinear optical properties were prepared. The nonlinear reverse saturable absorption measurements of composite materials were performed with a frequency-doubled Q switched Nd∶YAG laser with 8-ns laser pulse at 532 nm. The factors that affect the performance of reverse saturable absorption and optical limiting of the materials were discussed. A phenomenological model is used to describe optical limiting phenomena, it meets with the experiment results largely. The effect of saturable absorption of alkoxy phthalocyanine Pb is the best ones among these compounds. It is due to the improvement of its conjugate characteristics and avoiding low polymerization of molecules.