Abstract: The thiourea-intercalated kaolinite (TU-Kaol) was prepared by a three-step reaction and then was incorporated into polypropylene (PP) to prepare the flame-retardant compounds by melt blending. The flammable characteristics and mechanical properties were evaluated by limiting oxygen index, cone calorimetry and universal test machine. The results indicated that the peak heat release rate of the composite containing 1.5 wt% of TU-Kaol decreased significantly from 1 474 kW/m2 to 1 100 kW/m2 compared to pure PP, whereas their tensile strength increased from 35.3 MPa to 39.8 MPa.