The invention discloses a water-soluble rosin resin processing device and an application method thereof. The device includes a reaction kettle, a stirrer and a material inlet, wherein the stirrer is arranged above the reaction kettle, a defoaming stirring paddle, a stirring paddle and a propeller are arranged sequentially on a stirring shaft which is arranged at the lower part of the stirrer, andheating coils are distributed evenly at the upper part and lower part of the reaction kettle; the material inlet, an auxiliary material inlet and a manhole are formed in the top of the reaction kettle, and a thermal oil inlet, a material outlet and a jacket inlet are also formed in the bottom of the reaction kettle; and the reaction kettle is provided with a jacket and an inner wall sequentially from outside to inside, the jacket is connected with a jacket outlet, and a coil thermal oil outlet which is connected with the heating coils is formed in the upper part of the reaction kettle. The device has the advantages of a simple structure, uniform heating of materials, a more stable reaction, lower energy consumption and the like, and the rosin resin which is produced by using the method hasthe advantages of good water solubility, good stability, high viscosity, high hardness, good water resistance, environmental protection, no smell, transparency and other excellent indicators.