Straight- and curved-bar refining plates are two important types of plates commonly used in disc refiners in the papermaking industry. Theoretically, the curved-bar refining plate has a relatively uniform bar interaction angle, which indicates uniform refining effects. The bar angle of the curved bar was proposed and two typical curved-bar plates, the three-stage radial curved-bar plate and isometric curved-bar plate, were designed in this paper. The arc equations of the curved-bar center line and curved-bar edges were established and finally, the specific edge load (SEL) of the curved-bar plate was derived. The determination of bar parameters was discussed, which provides a theoretical basis for the design of curved-bar plates.