AbstractWith the rapid development of the packaging industry, the requirements for physical properties of corrugated paperboard tend to become higher and higher, especially for the strength properties. A water glass-starch compound system was employed as a surface sizing agent to improve the strength of linerboard in this work. The viscosity of water glass-starch compound system, and its impacts on ring-crush strength and bursting strength of linerboard were evaluated. Cobb value and contact angle were used to characterize the waterproof performance of paper after surface sizing. Compared with conventional surface sizing agents, water glass-starch compound system overcame the defects of low coating weight and inadequate stiffness of the sizing layer, allowing ring-crush strength and bursting strength of linerboard to increase by 91% and 50%, respectively. Additionally, the compound system had higher solids content, low viscosity, and good film-forming ability, which will bring a lot of convenience to production.