The invention relates to the field of packaging, in particular to a paper sheet locating mechanism on paper box packaging lines. Each packaging line comprises a bottom frame, a conveying chain, a paper sheet discharging device, a paper beating device, a gluing device, a strip discharging device, a folding and bonding device and a drive device. The paper sheet locating mechanism comprises the paper beating devices and the conveying chains. The conveying chains are provided with limiting blocks. Sting structures are arranged at the rear portions of the limiting blocks. Paper sheets are beaten by the paper beating devices so as to be fixed to the sting structures. The paper sheet locating mechanism on the paper box packaging lines is simple in structure, beating power is obtained from sliding motion of the conveyor belts, no drive device needs to be additionally arranged for the drive purpose, the paper sheets are beaten by the locating mechanism to the sting structures, the paper sheets are ingeniously and stably located on the conveying chains, and therefore packaging accuracy and production efficiency are greatly improved.