In this paper, the synergies of several smoke suppressants are studied. Herein, both main group components and sub-group components are investigated, including Mg(OH)2, Sb2O3, ferrocene, Cu2O. The experiments are designed following the orthogonal design, 4 factors and 3 levels. Nine samples are prepared. Cone calorimeter is used to characterize the smoking performance of the flame-retardant intumescent coatings. Results shows that, when the quality percentage of Mg(OH)2, Sb2O3, ferrocene, Cu2O are 2%, 1%, 2%, 1.5%, the smoke amount of intumescent coatings is minimum. At this point, the cooperation of smoke suppressants meets the best. While comparing to the original intumescent coatings, the total smoke rate decrease 14 %.