The invention relates to a waterborne 
polyurethane resin for a 
toluene reduced ultrafine 
fiber base and a preparation method and application of the waterborne 
polyurethane resin. The waterborne 
polyurethane resin is prepared by the following methods: performing a stirring reaction on 
polyester polyol, polyether 
polyol and diisocyanate at a temperature of 65-95 DEG C for 1-3 hours, successively adding a glycol type chain extension agent and a 
carboxylic acid type hydrophilic chain 
extender, and performing a chain extension reaction respectively so as to obtain a 
prepolymer; and cooling the 
prepolymer to a temperature less than or equal to 60 DEG C, adding a low 
boiling point solvent, performing uniform stirring, adding a neutralizing 
reagent, performing stirring for 0.5-2 hours, performingcooling to a temperature less than or equal to 40 DEG C, adding water, performing 
emulsion, after 
emulsion is completed, firstly adding a hydrophilic chain 
extender and a 
diamine type chain 
extender,performing chain extension respectively, after the operation, increasing the temperature greater than or equal to 70 DEG C, performing vacuum 
desorption of the 
solvent, and performing cooling and 
discharge, so as to obtain the waterborne polyurethane resin. The resin is used in preparation of the 
toluene reduced ultrafine 
fiber base, and the obtained base is high in bass thickness 
retention rate,soft and plump in hand feel, good in elasticity, high in tensile strength and good in 
tear resistance.