The invention relates to an aqueous blocked 
isocyanate curing agent, a preparation method therefor and an aqueous 
coating material. The aqueous blocked 
isocyanate curing agent comprises the followingraw materials: a polyisocyanate 
trimer, methoxy 
polyethylene glycol, polyether 
diol, a blocking agent, a cosolvent, 
alkali metal alkoxide and a neutralizer, wherein the polyisocyanate is at least oneselected from an aliphatic polyisocyanate 
trimer and an aromatic polyisocyanate 
trimer, the methoxy 
polyethylene glycol is one selected from polyglycol 
ether monoalcohols with the molecular weight of300 to 2,000, and the polyether 
diol has the molecular weight of 120 to 1,000. The aqueous blocked 
isocyanate curing agent can react with resin with active groups such as amino resin and 
polyester resin in a 
coating formula, a large number of 
soft segment structures are introduced into a 
coating film, the energy release of the coating film during stone 
impact stressing can be retarded, and then, the stone 
impact resistance of the coating film is improved, so that the coating film can have stone 
impact resistance under the condition of low film thickness.