The present invention is an improved sealing strip for sealing the toner chamber slot of a toner cartridge, and its manufacturing method. A sealing strip for toner cartridges includes a sealing film and a double-faced sealing film adhered thereto. The sealing film includes, along a first direction, a sealing portion for sealing a toner chamber slot of a toner cartridge and a pull part extending along one end of the sealing portion. The pull part is used for tearing away the sealing portion. The sealing portion includes two openings adjacent the pull part. The two openings range from 0.5 to 3.5 millimeters in length. The sealing film includes, along a second direction substantially perpendicular to the first direction, a prime layer and a guide layer. The guide layer includes two guide lines substantially parallel to each other and extending along the first direction. The two guide lines intersect the two openings. The double-faced sealing film is adhered to the sealing portion.