A new difunctional fluorene-based benzoxazine monomer was synthesized through the reaction of 9,9-bis-(4-hydroxyphenyl)-fluorene with formaldehyde and cyclohexylamine. The chemical structure was confirmed through FTIR, H NMR and 13C NMR analyses. The polymerization reaction of the precursor was monitored with Differential Scanning Calorimetry (DSC) and FTIR. The thermal properties of cured polymers were evaluated through DSC and Thermo Gravimetric Analysis (TGA). The fluorene-based polybenzoxazine showed that the typical curing characteristic of the oxazine ring-opening for difunctional benzoxazine centred at 251 ℃, with remarkably higher glass transition temperature (189.4 ℃) and better thermal stability than traditional biphenol A polybenzoxazines. The thermal decomposition temperature (5% weight loss) and the char yield of fluorene based polybenzoxazine at 800 ℃ is 329 ℃ and 31%, respectively.