Kraft paper capable of improving L-value brightness of paper surface, surface layer and production method thereof

The invention provides kraft paper capable of improving the L-value brightness of a paper surface, a surface layer and a production method thereof. The production method of the kraft paper surface layer comprises the following steps: providing filler: grinding calcium carbonate to obtain ground calcium carbonate, and conveying the ground calcium carbonate to a filler tank to serve as the filler; mixing the filler and a raw material slurry: diluting the ground calcium carbonate in the filler tank on line to obtain diluted ground calcium carbonate, and adding the diluted ground calcium carbonateinto the raw material slurry at an inlet of a sizing pump in the process that the raw material slurry passes through the sizing pump to obtain a surface layer slurry, which comprises 99wt%-88wt% of the raw material slurry and 1wt%-12wt% of the ground calcium carbonate; sizing the surface layer: spraying the surface layer slurry to a net part after passing through a slurry filling pump, a screen in front of a net and a he