Melamine-modified montmorillonite (MA-MMT) was prepared via cation exchange. The intercalation behavior was investigated by Fourier transform infrared spectrometer (FT-IR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The results showed that the d-spacing value increased from 1.25 nm for Na-montmorillonite (Na+MMT) to 1.53 nm for MA-MMT. Different kinds of montmorillonite combined with melamine pyrophosphate (MPP) were used to prepare flame-retardant polyamide 6 (FR-PA6). Flame retardance of FR-PA6 samples was investigated by limiting oxygen index (LOI), UL-94 vertical burning method, and cone calorimeter test. Morphology and component of char residues for FR-PA6 were investigated by scanning electron microscope (SEM) and XPS. It was found that MA-MMT/MPP system contributed both excellent flame retardance and anti-dripping ability for PA6. MA-MMT particles can fill flaws of char residues and strengthen the char layer, leading to form more intumescent char layer. POLYM. ENG. SCI., 51:377385, 2011. (C) 2010 Society of Plastics Engineers