Iso-octanol and trimellitic anhydride as the raw materials, SnO as the catalyst, TOTM was synthesized by the non-acid method. The effects of reaction temperature, reaction time, repeated use of catalyst and the way for refined on products were examined, the feasibility of the process was determined. Optimum process conditions were determined in the experiment: the filtrate was washed with insulation, then stripping, and finally decolorized with charcoal; the catalyst can be reused, and experimental procedure is simplified. The process is feasible, and has good prospects.