Aiming to impart epoxy resin (EP) with improved thermal stability, fire retardancy and mechanical property, inspired by core-sheath corncob structure, halloysite nanotubes were successively functionalized with bio-mimic polydopamine nano-coating (PDA) and ultrafine Fe(OH)3 nanoparticles to prepare hierarchically structural halloysite@PDA@Fe(OH)3 (Fig 1). The targeted product was verified via FTIR, XRD, XPS and TEM techniques. Resultantly, in the thermal degradation study, EP composite with halloysite@PDA@Fe(OH)3 possessed notably higher char yield than those of neat EP, EP/5halloysite, EP/5halloysite@PDA. Fire retardancy investigation revealed that 5wt% halloysite@PDA@Fe(OH)3 imparted EP with enhanced LOI value of 33.9% and UL-94 vertical burning rating of V-1, which was a significant improvement compared to the counterparts. In cone calorimeter test, EP/5halloysite@PDA@Fe(OH)3 gave rise to 41% reduction of peak heat release rate (pHRR) with respect to those of EP/5halloysite and EP/5halloysite@PDA. TG-FTIR test manifested that halloysite@PDA@Fe(OH)3 notably decreased volatile evolutions (CO, aliphatic compounds, aromatic compounds, and carbonyl compounds). In-situ FTIR, Raman spectra and SEM observations revealed the char with more compact and continuous structure and higher graphitized degree was acquired with halloysite@PDA@Fe(OH)3. In parallel, the tensile strength and modulus were enhanced with halloysite@PDA@Fe(OH)3, accompanied by the increase of dynamic storage modulus (G’). Finally, the possible mechanism to account for the improved fire retardancy was proposed, which was involved in the interfacial catalytic charring.