The invention discloses a method for preparing modified urea resin for coating abrasive tools. The method comprises the following steps of: adding formaldehyde at one time is a stoichiometric ratio, regulating the pH to be 7.5-10.0, adding the first batch of urea, heating to the temperature of between 50 and 80DEG C, controlling the reaction time to be 30-90 minutes, adding the second batch of urea, heating to the temperature of between 70 and 100DEG C, controlling the reaction time to be 30-90 minutes, adding a modifier of glycerol, regulating the pH to be 4.0-6.5, and reacting at the temperature of between 80 and 100DEG C for 10 to 60 minutes; and regulating the pH to be 7.0-10.0, keeping the temperature of between 69 and 90 DEG C, adding the third batch of urea and a modifier of soluble starch, and reacting for 10 to 60 minutes by keeping the temperature, adding modified hydroxy silicone oil, controlling the pH to be 7.0-9.0, reacting for 30 to 90 minutes, and finishing the reaction to obtain the urea resin for coating the abrasive tools, which is low in cost, stable in storage, and good in heat resistance and bonding strength.