The invention relates to a process for preparing
toluene diisocyanate (TDI) by using
toluenediamine and
dimethyl carbonate. According to the process, a deactivation catalyst, namely
zinc oxide (ZnO), of a reaction, which is used for synthesizing
toluene dicarbamate (TDC) through catalyzing
toluenediamine and
dimethyl carbonate by
zinc acetate, is used as a catalyst of a reaction for TDC decomposed TDI preparation, the deactivation catalyst, namely ZnO, of the reaction is not required to be separated from the product TDC and is directly applied to the reaction for TDC
decomposition catalyzed TDI preparation, and a TDC decomposed TDI preparation process adopts that
decomposition reactors of two stages are in series connection and a fractional condenser is arranged between the
decomposition reactors of two stages. According to the process, TDC is synthesized through catalyzing
toluenediamine and
dimethyl carbonate by
zinc acetate, and the deactivation catalyst, namely ZnO, of TDC synthesis is selected as an
efficient catalyst for TDC decomposition reaction, so that the
catalysis effect is good, and the yield of TDI is high; and the temperature of the TDC decomposition reaction is low, so that the total production cost can be greatly reduced.