Abstract: This invention puts forward a process of preparing butyl rubber. High gravity devices are used as polymerization reactor. The mixture of isomonoolefin and conjugated diolefin monomers and the diluent, and the mixture of the initiator and diluent are pumped at a certain ratio into a high-gravity reactor to conduct cationic polymerization in the high-gravity environment. After polymerization, the monomers and the diluent are removed from the product to obtain butyl rubber polymers with number-average molecular weight of 80000˜300000 and molecular weight distribution index of 1.9˜3.6. The high gravity polymerization method of this invention can tremendously intensify micro-mixing, mass transfer and heat transfer in the reaction. Compared to the conventional stirred polymerization method, this invention features small reactor volume, at least 30-fold shorter residence time of substances in the high gravity reactor, low cost, low energy consumption and high production efficiency.