The invention relates to a polymer cell sealing device on a production line. The polymer cell sealing device comprises a stander, wherein a base of the stander is provided with a lower heating block, the upper side of the lower heating block is provided with an upper heating block capable of moving up and down relative to the lower heating block, the lower heating block and the upper heating block are mutually cooperated to seal the polymer cell, the upper side surface of the lower heating block is provided with a flexible layer, so that the impact on the polymer cell can be buffered when the polymer cell is sealed. By adopting the polymer cell sealing device, the polymer cell can be rapidly and reliably sealed, the cell is unlikely to damage, and the application effect is good.