In this study, glycine (GLY) was introduced into layers of kaolinite (Kaol-GLY) by intercalated and replaced to further enhance the flame retardancy and thermal stability properties of polypropylene (PP) containing intumescent flame-retardant (IFR) composite after deeply characterized and analyzed. The results indicated GLY successfully intercalated into the layers of Kaol. The presence of 1.5 wt% Kaol-GLY could increase the limit oxygen index and char residues of PP (75.0 wt%)/ IFR (23.5 wt%) composite, and decrease the value of peak heat/ smoke release rate. Structure and morphology analysis of char by SEM and FTIR demonstrated that Kaol-GLY could contribute to improve the char quality of PP composite. Furthermore, this work can also provide a way for preparing intercalated Kaol with hydrophilicity amino acids compared to similar prior literature, and the flame-retardant mechanism of PP/ IFR composite was deeply speculated and analyzed based on thermogravimetric-infrared analysis and real-time-FTIR results under the presence of Kaol-GLY.