The invention provides a cooling device for preparation of HDI by a gas phase process. The cooling device includes a spray condensation area disposed between a reactor and a reaction collector, a first nozzle is disposed at the upper part of the spray condensation area, the first nozzle is connected to a chlorobenzene conveying pipe, chlorobenzene is sprayed in the spray condensation area throughthe first nozzle to cool and absorb HDI prepared by the reactor, so that HDI can be separated from other gaseous substances, the reaction collector is equipped with a gas outlet pipe and a drain pipe,and the drain pipe sends chlorobenzene containing HDI to a next procedure. Compared with the traditional technology, the device and method provided by the invention can save energy, achieve more thorough absorption of HDI by chlorobenzene, and reduce by-product generation, thus increasing the product yield, are beneficial to normal running of the reaction, also play a cooling role, prolong the normal production time, and reach the purpose of synergy.