A packaging bag line-folding and sealing machine includes a first sealing unit and a second sealing unit for sealing a packaging bag therebetween, a first rocker arm and a second rocker arm mounted at the first sealing unit, a locating block, a first link coupled between the first rocker arm and the locating block, two line-folding units, and two second links coupled between the second rocker arm and the line-folding units for moving the line-folding units to make folding lines on the packaging bag between the first and second sealing units upon movement of the first sealing unit relative to the locating block. The application of the packaging bag line-folding and sealing machine greatly improves the packaging quality of packaging bags, and allows adjustment of the line-folding units to fit different sizes of packaging bags, enhancing user convenience.