Method for synthesizing melamine cyanurate salt

The process of synthesizing melamine cyanurate includes the following steps: mixing urea, melamine and ammonium salt as dispersant in certain proportion to obtain mixture; pre-heating the reactor to 270-295 deg.c, starting the stirrer, leading nitrogen to the reactor, adding the mixture to the reactor, heating the material to 270-290 deg.c, and reacting for 60-70 min to obtain white powdered intermediate product; adding water in 14-18 times the weight of melamine to the intermediate product, heating to 100 deg.c, reacting for 10 hr, hot filtering, washing the filter cake with boiled water, stoving, and crushing to obtain melamine cyanurate product. The melamine cyanurate product of the process has purity of 99.5 % and yield up to 95.5 %, and is applied as fire retardant.