Rosin as a natural renewable resource has become an important research topic. The esterifiable rosin used to do the cation neutral sizing agent has the advantages of low dosage, good effect, and low demand for equipment. In this paper, the rosin esterification reaction temperature, reaction time had been made a detailed discussion. When the reaction temperature is 230°C, the reaction time is 6h, the dosage of ZnO (as the catalyst) is 0.2% (relative to the rosin), the acid value of rosin is the lowest, and the esterification has the most complete response. The emulsified rosin glyceride as the sizing was used in papermaking. The results showed that the sizing degree of paper was the highest when the dosage of sizing and Al2 (SO4)3 were both 1.5 %( relative to the dry pulp).