The phase states of the catalytic system of FeCl3-Al(i-Bu)3-pyridine are studied in the paper by means of the Tyndall effect, electron microscopy and super-filtration. It is found that the catalyst dispersing in the butadiene-hydrogasoline solution exists in small particles and the size of particle is 30 nm or so in diameter. The catalyst belongs to a multi-phase catalytic system. The active center of catalyst lies on the surface of nanometer particles, which are amorphous. The ratios of different components of catalyst affect the formation of the particles. With the optimum ratio, nanometer particles, which disperse more uniformly and are of highly catalytic activity, can be obtained.