The invention relates to a preparation method of 
flame-retardant core-shell-type 
acrylic resin, which comprises the following steps of: adding deionized water, emulsifying agent, 
methacrylic acid and monomers A for emulsification, starting to drop initiator when temperature reaches 75DEG C, keeping dropping time to be 1-3h, preserving heat for reaction for 3-5h, dropping ester compounds and keeping reaction time to be 1-3h to obtain core-layer 
emulsion; and simultaneously adding monomers B and initiator into the core-layer 
emulsion, keeping dropping time to be 1-3h, preserving heat at 75-85DEG C for reaction for 2h, dropping 
bentonite dispersion liquid with 
mass percent being 20 percent, preserving heat for reaction for 1-3h, dropping cross-linking agent, preserving heat for reaction for 1-2h, decreasing temperature to 50DEG C, adding emulsifying agent into a 
reaction system, keeping reaction time to be 30min, and adding 
ammonia water to regulate pH (potential of 
hydrogen) to 7-8 to obtain the 
flame-retardant core-shell-type 
acrylic resin. The obtained 
acrylic resin has the advantages that not only can the defect of hot sticking and cold shortness of the traditional acrylic resin be improved, but also the 
flame retardation of the acrylic resin can be improved.