Zinc ammonium phosphate/halloysite (ZAP/HNT) composites were synthesized by an adsorption-chemical precipitation method. To enhance the flame retardancy and mechanical properties of epoxy (EP), the Exolit^(R) OP 1230 flame retardant was employed in EP combining with ZAP/HNT. The ZAP/HNT and EP/ZAP/HNT were characterized by infrared spectroscopy（FT-IR）and scanning electron microscope (SEM). Results show that the particle size of ZAP is about 20～50 nm. The ZAP/HNT is dispersed uniformly in EP due to the strong reaction between the -OH and epoxy group. Thermal gravity(TG) analysis shows that the dehydrate and deamination occur during heating ZAP/HNT. The total mass loss of ZAP/HNT at 600 ℃ is about 11.34%. The residue mass of EP/ZAP/HNT at 790 ℃ is about 26%, indicating a good carbonization performance. The flame retardancy of composites was tested by micro-scale combustion calorimetry (MCC) and UL-94 methods. Compared to EP, the HRR of EP/ZAP/HNT（25%）is reduced to 58.82%. The synergistic effect of the flame retardancy between ZAP/HNT and OP 1230 was observed. The residue was characterized by energy dispersive spectrometer (EDS) and SEM. P, Al, Si and Zn elements are in the outer layer of the residue, indicating that flame retardants in combustion migrate to the surface under the action of gas, which can help to form a stable carbon layer composed of metal oxides such as pyrophosphate, carbon and Al₂Si₂O₅.