The invention provides N-full aromatic hydrocarbyl 
bisphenol-
diamine tetrafunctional 
fluorene-based benzoxazine and a preparation method thereof. A new N-full aromatic hydrocarbyl 
bisphenol-
diamine tetrafunctional benzoxazine 
monomer is obtained by the following steps: using 
trifluoroacetic anhydride to protect amino in 2, 7-dihydroxy-9, 9-bis-(4-amino phenyl) 
fluorene to produce 2, 7-dihydroxy-9, 9-bis-(4-trifluoroacetyl phenyl amino) 
fluorene, then performing 
Mannich condensation reaction of the 2, 7-dihydroxy-9, 9-bis-(4-trifluoroacetyl phenyl amino) fluorene and 
aliphatic amine and 
paraformaldehyde to produce a 9, 9-bis-(4-trifluoroacetyl phenyl amino) 
bisphenol fluorene-based benzoxazine 
monomer, then performing amino deprotection, and performing secondary 
Mannich condensation reaction with a phenolic compound and 
paraformaldehyde to finally obtain the new N-full aromatic hydrocarbyl bisphenol-
diamine tetrafunctional benzoxazine 
monomer. The problems that fluorene-based benzoxazine with a structure with larger steric hindrance is small in molecular weight, low in crosslinking density, and poor in 
toughness and thermal performance reduction caused by the introduction of flexible groups can be solved, and the 
processing properties of polymers can be improved.