The invention provides a spraying circulation reactor and a method for synthesizing isocyanate by using the spraying circulation reactor. Through the spraying circulation reactor, organic amine and solvent mixtures, and chlorine hydride or phosgene are efficiently mixed for reaction in a spraying device; then, the materials are sprayed out through a spraying nozzle of the spraying device; throughthe continuous spraying circulation reaction, the condition that the organic amine compound completely reacts to obtain isocyanate products is realized. The method provided by the invention has the advantages that the corresponding amine and chlorine hydride or phosgene can be fast mixed for reaction; the practical utilization rate of chlorine hydride or phosgene can be improved; the phosgene excessive quantity ratio is reduced; the reaction time is shortened; the occurrence of side reactions is effectively reduced; the yield of organic amine hydrochloride or isocyanate can be further improved.